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About Eye Disease

About Eye Diseases



Paediatric Eye Diseases and Strabismus

Normal


Short-sightedness


Short-sightedness (myopia) is the most common eye problem in the world. This phenomenon is even more prominent in Hong Kong. Studies show that 30 to 70% of primary school children in Hong Kong suffer from short-sightedness.

Short-sightedness is usually due to elongation of the eyeball. Thus, the object is focused in front of the retina. A child with short-sightedness typically complains of blurry vision for distant objects, but is less so when seeing near objects. The child will have difficulty in reading the blackboard and he might also squint his eyes when looking at distant objects.


Long-sightedness


Long-sightedness (hypermetropia or hyperopia) is less common than short-sightedness amongst Hong Kong children. Long-sightedness is due to relatively short eyeball.

The symptoms of long-sightedness are less obvious than short-sightedness. If a child only has mild longsightedness (less than 2D or 200 degrees), the elasticity of his lens helps to keep things in focus and he or she can see rather clearly. However, if the child has severe longsightedness, he or she will have difficulty in focusing and thus will see poorly. The child may even develop squint (strabismus) and lazy eye. Under these circumstances, the child must wear glasses.


Astigmatism



In astigmatism, the curvature of the cornea is different along different axes. As a result, light rays entering the eye are focused at different points instead of a single point. This will create a blurry image. The child may suffer from eyestrain. He may squint his eyes or adopt a head tilt. A child with high astigmatism requires glasses.


Prevention of Progression of Short-sightedness
While wearing spectacles or contact lenses can improve vision for children with short-sightedness, both methods may cause inconvenience and wearing contact lens may even give rise to complications.

High myopia is associated with higher chance of eye diseases, such as retinal detachment, macula haemorrhage, cataract and glaucoma etc.

The causes of short-sightedness are still unknown, so are those of short-sightedness progression. Both genetic and environmental factors play a role. Shortsightedness progression is more significant in children between 6-12 years old.

Atropine eye drops
Studies on the effectiveness of atropine eye drops (0.5 to 1.0%) in reducing short-sightedness progression started as early as in the 70s. Atropine is a non-selective anti-muscarinic blocker. It can inhibit excessive scleral growth and thus reduce or arrest short-sightedness progression. Studies showed that 0.5% and 1.0% atropine eye drops can slow short-sightedness progression by 75% and 80% respectively. On the other hand, atropine will cause pupil dilation and inhibit accommodation (zooming of focus to see near things), causing photophobia (light sensitivity) or blurry vision when seeing near objects. Photochromatic and progressive lenses may hence be required in children using atropine eye drops.

Recent studies showed that using lower concentration of atropine eyedrops (0.01 to 0.1%) can slow shortsightedness progression with less side effects. Atropine (0.01%) can reduce progression by 60%, but the average increase in pupil dilation is only about 1mm and 95% of children do not require progressive lenses for near vision.

In summary, topical atropine can slow down shortsightedness progression in children. However, its application has to be considered on individual basis. Regular monitoring is needed when using the eyedrops.

Can progressive lens arrest or reduce short-sightedness progression?
One of the hypotheses of preventing short-sightedness progression is to control accommodation. Progressive lens is a specially designed lens to achieve this purpose. A progressive lens is a one-piece lens whose shortsightedness power varies gradually from a highest value in the upper portion to a lowest value in the lower portion. The child is asked to use the upper portion for viewing distant objects and the lower portion for nearer objects. However, the evidence for arresting or preventing shortsightedness progression by progressive lens is very weak and not well established.

Can contact lens arrest or reduce short-sightedness progression?
Some studies found that there was no difference in shortsightedness progression between children wearing Rigid Gas Permeable (RGP) lens and those wearing spectacles.

Orthokeratology (Ortho-K, OK lens), which was introduced in the 70s, uses tight-fitting, flat, rigid contact lenses to decrease the curvature and refractive power of the cornea. Lenses are changed periodically to progressively flatter ones. After the cornea has been sufficiently flattened, retainer lenses are usually worn at night to preserve the modified shape, otherwise the eye will revert back to the original corneal curvature and refraction. Parents must be aware that there are potential risks associated with contact lens wearing, such as corneal abrasion, ulcer and infection, leading to permanent loss of vision.


Strabismus (Squint)
Strabismus (squint) is a condition in which the eyes are misaligned. The two eyes point towards different directions. One eye is fixed at the object of interest, while the other eye is misaligned to a different direction. The misaligned eye may be directed inward (convergent squint), outward (divergent squint) or upward (vertical squint).

A child with squint will only use the properly aligned eye to see. The image from the misaligned eye will be suppressed. This will lead to loss of binocular vision and may even cause lazy eye. Squint also causes a cosmetic problem that will affect the child's self-esteem.

In most cases, squint is caused by improper eye muscle balance. However, in a small number of children, squint is caused by serious underlying eye diseases such as congenital cataract, cancer of the eye, etc. Therefore, we should never neglect a squint.

Treatment of squint includes glasses, patching, vision training and surgery. Some people have a misconception that children will outgrow their squint. Actually these people have confused true squint with pseudo squint. In a child with pseudo squint, his eyes are actually normal and are well aligned. He has a wide and flat nose bridge which gives the illusionary appearance of crossed eyes. As he grows older and the nasal bridge becomes higher, this illusionary appearance of crossed eyes will disappear. However, in a child with true squint, his eyes are misaligned. This condition will not outgrow. He needs early treatment to straighten the eyes and allow normal vision to develop.

Convergent SquintDivergent SquintVertical Squint
Head Tilt Caused by
Vertical Squint


Lazy Eye (Amblyopia)
During the first 8 years of life, the visual system is in a developmental stage. Though a newborn infant is able to see, his vision will continue to develop with proper use of his eyes. If proper use of his eye is hindered, the vision of that eye will not develop properly, and that eye will become a lazy eye. A lazy eye has poor vision and is not correctable with glasses.

The reasons that hinder visual development include firstly, misaligned eyes. Secondly, it could occur when one eye is out of focus with respect to the other because of a stronger degree of short-sightedness, long-sightedness or astigmatism. The more out-of-focus eye “turns off” and becomes lazy. Thirdly, droopy eyelid and eye diseases like cataract that inhibit light from entering the eye also lead to lazy eye.

Droopy Eyelid Congenital Cataract

Lazy eye commonly occurs in only one eye of a child. Parents might not be aware that their child is only seeing the world with one eye unless they bring their child for a formal eye examination. If lazy eye is detected in early childhood, it can be corrected by patching the normal eye. However, after the age of eight, lazy eye becomes irreversible.

Treatment of Lazy Eye with Occlusion

Normal VisionAmblyopic Vision


Eye Examination
A young child will not be able to tell you of his visual problems. Therefore, parents should bring their child for a comprehensive eye examination. A comprehensive eye examination can tell you whether the child has short-sightedness, long-sightedness, astigmatism, squint, lazy eye or any other eye diseases. If an abnormality is detected, early treatment can be offered. If the eyes are found to be normal, this would be a piece of useful baseline information for future reference.

An eye doctor is able to examine a child of any age and also check whether the child has focusing problems. For infants, the eye doctor might need to use special techniques, instruments or diagnostic eye drops.

Children should have annual comprehensive eye examination after the age of 4. Eye examination is paramount importance if you notice following conditions in your children:
  • An infant who has abnormal visual response. For example, he does not respond to light or follow toys and cannot recognize the face of his parents.
  • The eyes have abnormal external appearance (e.g. droopy eyelids, redness and swelling of the eyes, bulging eyeballs, or white reflex from the pupils, etc.)
  • Frequent tearing, blinking and rubbing of eyes.
  • Blurred vision, double vision.
  • Abnormal alignment of eyes, e.g. eye turned inward, outward or upward.
  • Head tilt when looking at objects.
  • Screwing of eyes when looking at objects or when copying from the board.
  • Any other condition that makes you worried.
Squint AssessmentAssessment of Stereopsis
Droopy Eyelid Congenital Cataract
Head Tilt Caused by
Vertical Squint
Treatment of Lazy Eye with Occlusion

Eyes Diseases of the Elderly

Common Eye Diseases of Seniors
Like the rest of our body, our eyes undergo changes as we grow older. Many people are under the misconception that deterioration of eyesight in seniors is inevitable and untreatable, resulting in the neglect of due eye care. The fact is, modern advances in the eye care field have brought methods of prevention and cure to many common senior eye diseases. This website aims to provide you with some general information on common eye diseases as well as their prevention and cure.


1. Cataract
Cataract is the clouding of our crystalline lens. It obstructs the passage of light into the eye, which affects vision. Patients feel as though they are seeing through very dirty glasses. Cataract can be caused by many reasons, the most common of which is age-related lens degeneration. Common symptoms are as follows:
  • Blurry vision, especially at night
  • Sensitivity to light, seeing shadows or halos
  • Frequent change of glasses with no improvement in vision
  • Colours appear darker, greyer and duller
The modern treatment method for cataract is surgical removal of the cloudy lens and placement of a permanent artificial implant. A frequently asked question from patients is "When do I need cataract surgery?". The answer is: when you feel that your daily life is affected by your unsatisfactory vision, you should consider cataract surgery. You do not need to wait until the cataract progresses into an advanced stage. The success rate of modern cataract surgery is extremely high and brings with it the additional benefits of improving your pre-existing near-sightedness, far-sightedness, astigmatism and presbyopia. Your doctor can further explain in detail when you undergo an eye examination.


2. Glaucoma
In Hong Kong, glaucoma is a common cause of blindness, with elderly people at a higher risk. Glaucoma is classified into acute, chronic, congenital and secondary. Chronic glaucoma is the most common type, accounting for 60-70% of all glaucoma cases. Early glaucoma often goes unnoticed by patients because there would be no pain or any effect on vision at this stage. But the increase in eye pressure will gradually damage eye nerves and reduce the visual field, ultimately leading to blindness. Therefore, it is strongly recommended that senior people, especially those with a family history of glaucoma, should undergo regular eye check-ups.

There are several methods to treat glaucoma, namely medicine, laser and surgery. Although glaucoma is a potentially blinding disease, it can be controlled if discovered in its early stage.


3. Age-Related Macular Degeneration
Macula is a special area in the central retina, made up of many small and sensitive nerve cells. We need a healthy macula to see details, read and see colours. When the macula is diseased, vision will be reduced and/or distorted.

Macular degeneration is mostly age-related. In Asia, there has been an increasing incidence of macular degeneration in recent years. High near-sightedness is also a major cause of macular degeneration. Much research has been devoted to discovering safe and effective treatment for the disease. Some are best treated with laser or intraocular injection of special medicine, while others may need special magnifying devices.


4. Diabetic Retinal Diseases
Diabetic retinal diseases are due to small blood vessel abnormalities caused by diabetes, resulting in a series of complications in the ocular fundus, including macular bleeding, swelling, lipid leakage, new abnormal blood vessel growth, vitreous bleeding, retinal detachment, glaucoma, etc. Such retinal diseases can cause blindness if they are not treated promptly. In the early stage, you may not notice visual changes; the diseases can only be discovered by eye examination. Therefore, patients with diabetes should have regular eye examinations and follow-up appointments.

Diabetic retinal diseases can be treated with laser or special medication to prevent serious complications, such as fundus bleeding, retinal detachment and neovasular glaucoma, which can cause blindness.


5. Floaters
Floaters is a very common symptom among the elderly, mostly caused by degeneration of the vitreous gel inside the eyes. They usually come and go without affecting vision. As long as the retinal problems are ruled out during eye check-ups, no treatment is required. However, serious retinal or vitreous diseases, such as vitreous haemorrhage, retinal tears or detachment can also cause acute onset of floaters. Therefore, it is important that you consult an ophthalmologist at the earliest opportunity for a detailed check-up if you start seeing floaters.


6. Dry Eyes
Human eyes have tear glands which produce tears for our eyes. There are two kinds of tear glands: the small glands which constantly produce small amount of tears that lubricate eyes to keep them healthy and comfortable; and the bigger glands that make a large amount of tears when we cry or experience discomfort in our eyes, as in the case of dry eye condition. Many middle-aged or elderly people (especially women) suffer from dry eye condition due to the dysfunction of small tear glands. Therefore, the big glands will overcompensate and produce too much tears. With the use of lubricating eye drops, the big tear glands will reduce tearing. Other conditions, such as tear duct blockage, can also cause tearing eyes. You will need to consult an ophthalmologist for proper treatment.


7. Presbyopia (Difficulty in reading or seeing near objects)
The normal human eye is capable of adjusting its focus due to small eye muscle functions and elasticity of the lens, which decline with age. Presbyopia usually appears after 40 years of age, and the eye would become like a camera which is not equipped with auto-focus. If you are nearsighted, you may notice that it is easier to read without reading glasses. However, those with far-sightedness may find reading increasingly difficult. Presbyopia can be corrected by glasses. Recently, there are presbyopic contact lenses available. Another option is to have your presbyopia treated with cataract surgery.

Refractive Errors



In a normal eye, light rays pass through the cornea and lens and focus on the retina, and a sharp image is perceived by the brain. It is like a camera lens focuses light onto a film.

Refractive errors occur when light rays pass through the eye but cannot focus on the retina and blurred images are formed. This is due to factors such as shape of the cornea, lens and length of the eyeball.


Types of Refractive Errors:

Near-sightedness (Short-sightedness)


A near-sighted eye is longer than normal, so light rays focus in front of the retina. Close objects can be seen more clearly while distant objects look blurred.


Far-sightedness (Long-sightedness)


A far-sighted eye is shorter than normal, so light rays focus behind the retina. Distant objects can be seen better while close objects look blurred.


Astigmatism


Many people with myopia or hyperopia have some degree of astigmatism. This is caused by uneven curvature of the cornea or lens. Astigmatism distorts the light rays entering the eye and focus unevenly on the retina. Objects look distorted and blurred.


Presbyopia


In a normal eye, light rays of close objects focus behind the retina, which is similar to a far-sighted eye looking at distant objects. The lens of a normal eye can change its shape and therefore refocus light rays on the retina, so a sharp image is formed. This process is called accommodation and it is automatic. With increase in age, the lens of the eye loses its flexibility and becomes less able to change its shape to accommodate. When people reach forties, tasks such as reading small prints become difficult.

Treatment for Refractive Errors in adults
1. Use of glassess / contact lens
2. Refractive Surgeries



Prevention of progression of short-sightedness in children
While wearing spectacles or contact lenses can improve vision for children with short-sightedness, both methods may cause inconvenience and wearing contact lens may even give rise to complications.

High myopia is associated with higher chance of eye diseases, such as retinal detachment, macula haemorrhage, cataract and glaucoma etc.

The causes of short-sightedness progression. Both genetic and environmental factors play a role. Short-sightedness progression is more significant in children between 6-12 years old.

1. Atropine eye drops
Studies on the effectiveness of atropine eye drops(0.5% to 1.0%) in reducing short-sightedness progression started as early as in th 70s. Atropine is a non-selective anti-muscarinic blocker. It can inhibit excessive scleral growth and thus reduce or arrest short-sightedness progression. Studies showed that 0.5% and 1.0% atropine eye drops can slow short-sightedness progression by 75% and 80% respectively. On the other hand, atropine will cause pupil dilation and inhibit accommodation (zooming of focus to see near things). Photochromatic and progressive lenses may be required in children using atropine eye drops.

Recent studies showed that using lower concentration of atropine eyedrops (0.01% to 0.1%) can slow short-sightedness progression with less side effects. Atropine (0.01%) can reduce progression by 60%, but the average increase in pupil dilation is only about 1mm and 95% of children do not require progressive lenses for near vision.

In summary, topical atropine can slow down short-sightedness progression in children. However, its application has to be considered on individual basis. Regular monitoring is needed when using the eyedrops.



2. Can progressive lens arrest or reduce short-sightedness progression?
One of the hypotheses of preventing short-sightedness progression is to control accommodation. Progressive lens is a specially designed lens to achieve this purpose. A progressive lens is a one-piece lens whose short-sightedness power varies gradually from a highest value in the upper portion to a lowest value in the lower portion. The child is asked to use the upper portion for viewing distant objects and the lower portion for nearer objects. However, the evidence for arresting or preventing short-sightedness progression by progressive lens is very weak and not well established.

3. Can contact lens arrest or reduce short-sightedness progression?
Some studies found that there was no difference in short-sightedness progression between children wearing Rigid Gas Permeable (RGP) lens and those wearing spectacles. Orthokeratology (Ortho-K, OK lens), which was introduced in the 70s, uses tight-fitting, flat, rigid contact lenses to decrease the curvature and refractive power of the cornea. Lenses are changed periodically to progressively flatter ones. After the cornea has been sufficiently flattened, retainer lenses are usually worn at night to preserve the modified shape, otherwise the eye will revert back to the original corneal curvature and refraction. Parents must be aware that there are potential risks associated with contact lens wearing, such as corneal abrasion, ulcer and infection, leading to permanent loss of vision.

Cataract

Cataract is the clouding of the crystalline lens. The crystalline lens is like the autofocusing lens of a camera. It focuses an image automatically onto the retina. When the lens becomes opaque, it is called cataract.

Do I Have Cataract?
Vision becomes blurry in people suffering from cataract. You will see glare under sunlight or strong lights. Sometimes, you will see double or several ghost images and coloured objects may lose their original tone. Some presbyopes may find that they can read without reading glasses because their myopia has increased. They also notice that they cannot see distant objects clearly. The lens becomes white when the cataract is mature and vision drops to hand motion or light perception. Hypermature cataract may cause complications like glaucoma and uveitis, which may cause eye redness, eye pain, photophobia, headache, nausea and vomiting.

Colour loses its
original tone
Vision becomes blurry
in cataract patients


How Is Cataract Formed?
Cataracts occur most frequently in senior patients. Chemical changes accumulate in the lens protein as a natural degenerative process and the lens becomes opaque. Younger patients can also suffer from cataract especially when they have high myopia, diabetes mellitus or other inherited degenerative diseases. Secondary cataract can also result from ocular trauma, long term use of steroids, and long- term exposure to ultraviolet light or infrared rays.

Cataract One day after surgery


Can Cataract Be Cured by Eyedrops or Oral Medications?
There are no medications that can reverse the process of cataract formation. At present, cataract can only be treated with surgery and intraocular lens implantation.


Advanced Surgery Restores Vision and Reduces Refractive Errors
Early cataract has little effect on vision and no treatment is necessary. Changing your glasses prescription can sometimes restore vision if the cataract has induced a refractive change. When there is a significant decrease of vision which affects your work or your daily life, cataract extraction is indicated. It is not necessary to wait until the cataract becomes mature. Traditional cataract surgery employs a large limbal incision, extraction of cataract and implantation of an intraocular lens. The wound is then closed with very fine sutures. The more advanced cataract surgery involves a small corneal incision, phacoemulsification and implantation of a foldable lens. Usually no suture or only one suture is required to close the wound because the small incision is self-sealing. Surgery may be performed with topical anaesthesia or other forms of anaesthesia as indicated.

 
Corneal incisions, capsulotomy, lens fragmentation by femtosecond laser Ultrasonic
phacoemulsification
implantation of foldable
intraocular lens


Bladeless Laser Cataract Surgery
Laser cataract surgery is a revolution in cataract surgery with unparalleled precision and reproducibility. The employment of femtosecond laser rays enables the surgery to be performed without the need for surgical blade, resulting in a safe and perfect cataract operation.

The first step in Femtosecond Laser Cataract Surgery is an assessment of anterior segment structures by high technology imaging techniques, which scan the cornea, anterior segment of the eye and determine the anterior and posterior surfaces and the thickness of the cataract. With these measurements, the surgeon plans the steps to be performed by the femtosecond laser. The femtosecond laser will perform anterior capsulotomy, form a round opening in the capsule, divide the cataract into multiple pieces and make the corneal incisions. With the use of laser, corneal incisions could be made without any blade cutting the eye. A lower dose of ultrasound will be required for phacoemulsification. This reduces the surgical risk of cornea damage, and allows for speedier recovery.

This revolutionary technology increases safety and precision in cataract surgery.

Advantages of Laser Cataract Surgery:
  • Laser cuts are very precise
  • Increases predictability in postoperative refraction results
  • The cataract is divided by and all entry points made with laser precision, resulting in a bladeless procedure
  • Complicated cases and very hard cataracts can be handled more easily with lower dose of ultrasound energy
  • Tighter wound and less risk of infection


Intraocular Lens
If you have myopia, hyperopia astigmatism, or presbyopia, they can be corrected with appropriate intraocular lens.

Depending on pre-operative planning and post-operative refraction, you may still need glasses or contact lens to correct any residual refractive error.

Different foldable intraocular lenses


Monofocal Lens Implants
Basic Lens: A Basic Intraocular Lens Implant is a fixed single focus lens that is designed to improve vision at just one distance, either far or near. The potential drawback is that after surgery you will probably need to wear glasses for near or far vision, even if you have never worn any glasses before surgery.

Toric Lens: Many people have some degree of astigmatism (oval shaped cornea instead of the round shape), but a minor level of astigmatism is considered normal and requires no correction. For patients with moderate to high degrees of astigmatism, you can choose to have your astigmatism permanently reduced by having a Toric Lens Implant, but still, you will need to wear glasses for near or far vision.

Presbyopia-Correcting Lens Implants
Presbyopia is the natural age-related loss of flexibility of your lens to focus from far to near or vice versa, requiring you to use reading glasses, bifocals or multifocals spectacles. Moreover, cataract surgery itself also induces presbyopia since your own accommodating lens is removed.

Multifocal Lens: Multifocal Lens Implants are manufactured with very fine rings with multiple powers. so you can see well at far and near focusing points. They do not require any muscular activity in your eyes for focusing, but a period of adjustment is necessary to learn to use this new optical system. The compromise is that there is a greater chance of seeing halos or rings around lights, glare and unclear vision as compared to a basic monofocal lens. Over time most people get accustomed to these disturbances and less prone to notice them, while others may continue to notice them long after surgery. You may have some difficulty distinguishing an object from a dark background, especially in areas with less light. You should take extra care when driving at night. Toric Multifocal Lens ar also available to correct astigmatism at the same time.


Laser Capsulotomy after Cataract Surgery
The transparent capsule that supports the intraocular lens may become cloudy after 1-2 years. A simple laser capsulotomy can restore the vision in a few minutes.

Glaucoma

Glaucoma is one of the leading causes of blindness in Hong Kong. Out of every one hundred adults above the age of 40, two or more may be affected by glaucoma. If we can diagnose glaucoma early in the course of the disease, blindness can often be prevented.

Leading Cause of Permanent Blindness
Symptoms may not be evident in early glaucoma, therefore the condition is often neglected. By the time the patient realises that he has an eye problem, the disease may already be very advanced. Therefore glaucoma is often nicknamed "the silent killer of vision"


What Causes Glaucoma?
Within the eyeball, there is a continuous flow of a transparent liquid called "aqueous humour". The flow of the aqueous humour is analogous to a sink with a faucet turned on at all times. If the flow is too fast or if the drainpipe gets clogged, the pressure within the eye increases. The increased eye pressure will damage the eye and its nerves, leading to poor vision and even blindness.

The diagnosis of glaucoma includes state-of-the-art tests and careful examinations by experienced eye specialists.
What Causes Glaucoma


Types of Glaucoma
Glaucoma can be classified according to the type of onset or underlying etiology as acute or chronic, congenital or acquired, primary or secondary, and normal tension glaucoma or hypertensive glaucoma.

Acute Glaucoma
Acute Glaucoma
Patients with acute glaucoma will experience a sudden onset of eye pain, redness, blurred vision and halos. It is usually associated with headache, nausea and vomiting. This is an ophthalmologic emergency, and medical attention should be sought immediately. Oral medication, injections or eye drops should be given in order to decrease ocular pressure as quickly as possible, after which treatment can be administered via laser peripheral iridotomy or other surgical methods.

Chronic Glaucoma
Chronic Glaucoma
Chronic glaucoma is more insidious. There are no telltale symptoms. Vision deteriorates and the field of vision narrows gradually. Patients are often unaware of their problem until the disease becomes very advanced, by which time most of their vision is lost. Hence glaucoma is nicknamed "the thief of sight".

Congenital /Acquired Glaucoma
Congenital /Acquired Glaucoma
While many patients are first diagnosed with glaucoma after the age of 40, there are also children who are born with a defective aqueous drainage system, resulting in congenital glaucoma. Congenital glaucoma usually presents itself during infancy or early childhood. Patients have large watery eyes which are sensitive to light.

Primary Glaucoma
Primary glaucoma refers to those not caused by systemic diseases (e.g. diabetes mellitus) or underlying eye diseases (e.g. cataract, uveitis)

Secondary Glaucoma
Secondary Glaucoma
Secondary glaucoma is caused by other underlying eye or systemic diseases, such as hyper-mature cataract, uveitis, eye tumours, diabetic eye disease or long-term use of steroid eye drops. It is vital to treat the underlying eye disease before the secondary glaucoma can be treated.


Normal Tension Glaucoma
Some patients can have symptoms and visual field loss typical of glaucoma even with normal intraocular pressure. This is called “normal tension glaucoma” in which the optic nerves apparently cannot withstand the “population-normal” level of eye pressure. Thus, more investigations are usually required for diagnosis.


Hypertensive Glaucoma
In general, glaucoma is caused by increased pressure inside the eyeball, thus damaging the optic nerves and causing vision deterioration and narrowing of the field of vision.


Those with the following conditions are at higher risk for glaucoma, and should undergo eye check-ups regularly:
  • Family history of glaucoma
  • High myopia
  • Diabetes mellitus
  • Ischemic heart/cardiovascular disease patients may benefit from regular eye check-ups, although their exact causal relationship with glaucoma is yet elucidated
  • Sleep Apnea
  • Migraine
  • Underlying eye conditions, e.g. uveitis, history of eye injury


Treatment of Glaucoma
Depending on the type of glaucoma, eye-drops, oral drugs, laser or surgery may be prescribed to control the eye pressure. In some patients with glaucoma in only one eye, prophylactic laser peripheral iridotomy or drug treatment may also be advised for the fellow eye to prevent acute glaucoma.

Glaucoma may cause permanent blindness, which can be prevented by early diagnosis and treatment. Adults over 40 years of age, especially those with the above risk factors, are recommended to undergo eye examination every one to two years to facilitate early detection and prevent deterioration.


Corneal Diseases

The Department of Ophthalmology provides a wide range of treatment options for various corneal diseases. Over the past few years, wide-ranging treatments have been introduced to manage difficult and complicated cases of corneal diseases.

Treatment for Keratoconus

1. Corneal Collagen Crosslinking
This surgery was introduced in 2009 for the treatment of keratoconus. Since then, hundreds of patients have already benefited from this procedure and have their condition stabilised without the need of corneal transplantation. Our technology has also been ungraded recently to achieve faster and more stable results.

2. Intracorneal Stromal Rings (ICRs) Implantation
Intracorneal stromal rings have been provided for the treatment of keratoconus since 2009. While the cornea can be stabilised using collagen crosslinking technology, Implantation of stromal rings can reduce the keratoconus-induced irregularities and thus improve vision.



3. Topographically Guided Surface Ablation
This technology has been developed to treat corneal irregularities. It has also been used in patients with keratoconus. Under the guidance of “corneal maps”, laser is transmitted to specific locations to reduce corneal irregularities. It is effective in treating corneal scars and corneal irregularities caused by other diseases or traumas.


Corneal Transplantation

We offer all types of corneal transplantation with an option to apply donor tissue from overseas eyebank, thereby greatly reducing the waiting time for surgery.

1. Penetrating Keratoplasty
Penetrating Keratoplasty involves the removal and replacement of all layers of corneal tissues. During the procedure, a circular cutting device is used by surgeon to cut the donor cornea and remove a circular disc of cornea. A second device is then used to remove a similar sized portion of the patient's cornea. The donor tissue is then sewn in place with sutures.



Penetrating Keratoplasty is now replaced by the technique described below in many situations. It is now reserved for specific disease entity only.

2. Lamellar keratoplasty/Deep Anterior Lamellar Keratoplasty
During this procedure, the anterior layers of the central cornea are removed and replaced with donor tissues. Endothelial cells and Descemets membrane (and part of the stroma in case of Lamellar keratoplasty) are left in place. This technique is used to treat anterior corneal opacifications and scars.

3. Endothelial Keratoplasty
This relatively new procedure has revolutionised the treatment of disorders of the innermost layer of the cornea (endothelium).It replaces the patient's endothelium with a transplanted disc of posterior stroma/Descemets/endothelium (DSEK/DSAEK) or Descemets/endothelium (DMEK). Unlike a full thickness corneal transplant, this surgery can be performed with one or no suture. Patients may recover functional vision in weeks to months as opposed to up to a year with full thickness transplants.

The patient's corneal endothelium is removed and replaced with donor tissue. With DSAEK, the donor tissue includes a thin layer of stroma, as well as endothelium, which is commonly 100–150 µm thick. With DMEK only the endothelium is transplanted. In the immediate post-operative period the donor tissue is held in position with an air bubble placed inside the eye (the anterior chamber). The tissue self adheres in a short period and the air is adsorbed by the surrounding tissues.

4. Artificial Cornea

The Boston Keratoprosthesis (KPro) is the most widely used artificial cornea or keratoprosthesis. It is a treatment option for corneal disease not treatable with corneal transplant techniques mentioned above or for patients with multiple cornea graft rejections.

Vitreomacular Retinal Diseases

What Are Floaters?
The jelly-like substance filling the space between the crystalline lens and the retina is called “vitreous humour”. The vitreous humour degenerates and liquefies when we get older, at which time we start to see floaters. Floaters can be moving opacities of various shapes and sizes (dots, circles, lines or spider webs). Physiological floaters usually occur when we are looking at a bright homogenous background such as a white wall or the blue sky. The floating opacities are few in number and remain unchanged over time. They represent normal physiological changes of the vitreous humour.

Pathological floaters appear suddenly and may occur in great numbers. They may suggest bleeding within the vitreous humour, inflammation of the uvea or separation of the posterior vitreous humour from the retina. If the floaters are accompanied by flashes or visual field defects, it may indicate retinal tear or retinal detachment. An ophthalmologist should be consulted immediately to distinguish the causes of these conditions.


Vitreous degeneration


Flashes, Acute Posterior Vitreous Detachment and Retinal Detachment
As we age, the vitreous humour undergoes the processes of synchysis (liquefying) and syneresis (dehydrating and shrinking). These are normal age- related degenerations. When the vitreous humour contracts and detaches from the retina, it is called acute posterior vitreous detachment (acute PVD), at which time sudden onset of floaters and flashes occur. Floaters can be caused by vitreous opacities or haemorrhages, whereas flashes are caused by the vitreous humour pulling on the retina. An urgent dilated eye examination is essential to check for retinal tears, which should be repaired with laser as soon as possible, to prevent it from evolving into retinal detachment within a few hours.


Posterior vitreous detachment

Retinal tear and detachment



What Are the Symptoms of Retinal Detachment?
  • Increased floaters
  • Increased flashes
  • Visual field loss
  • Visual distortion or disturbance



Treatment for Retinal Detachment
Retinal degenerations or tears can be repaired with laser while retinal detachment is treated with surgery. There are two main types of retinal detachment surgery, namely scleral buckle, which is performed around and outside the eyeball, and vitrectomy (with gas or silicone oil injection), which is performed inside the eyeball. Both of the surgeries include laser treatment or cryotherapy.


Vitrectomy


Who Are at Risk of Retinal Detachment?
  • Middle-aged persons with PVD which causes retinal tear
  • Eyes with retinal lattice degenerations, atrophic holes or horse-shoe tears
  • High myopes (higher than –6.0 Dioptres)
  • Ocular or orbital trauma
  • Previous intraocular surgery (e.g. cataract or glaucoma surgery)
  • Certain inherited diseases (e.g. Marfan's Syndrome, Stickler's Disease)
  • Family history of retinal detachment
  • Diabetic retinopathy
  • Retinopathy of prematurity, etc.


The Latest Development in Maculopathy Treatment
The retina is like a camera film: it functions by capturing the light from objects. The image directed onto the retina is then transmitted to the brain where it is processed. Structurally speaking, the retain is more like a part of the brain with no capacity for self-repair or transplantation. In the centre of the retina is the macula, which is responsible for central and colour vision. If left undiagnosed and untreated, all types of maculopathies can lead to severe consequences, e.g. blurred central vision, central visual field defects or distorted images. Some conditions are asymptomatic, especially when they affect one eye only or are in slow progression. Thanks to the advances in clinical technology and a better understanding of macular diseases, those that were considered incurable in the past can now be treated by surgery.

Treatment of Macular Hole
A macular hole is a break of optic nerve tissues in the centre of macula. It is mostly age-related or caused by severe myopia. The standard treatments are subtotal pars plana vitrectomy with removal of the posterior hyaloid, followed by removing the internal liniting membrane (Photo 1) and gaseous and fluid exchange. Most patients are not required to maintain a face down posture post-operatively. The success rate is over 90%.

maculopathy
Photo 1: During surgery (the right eye of patient from the surgeon's perspective):the internal limiting membrane near the macular hole (arrow) is lifted(arrow)using an intraocular forceps.

Treatment of Proliferation of Macular Epiretinal Membrane
Proliferation of macular epiretinal embrane (Photo 2) is one of the common eye diseases in Hong Kong, the treatment of which is to remove the vitreous body and epiretinal membrane. Outcome can be improved with internal limiting membrane removal. The recurrence rate after first surgery is low.

maculopathy
Photo 2: Macular epiretinal membrane disease in a patient with severe myopia (before surgery).

Treatment of Maculoschisis
Those with myopia of over 600 degrees have severely elongated eyeballs, which stretch thin the macula. The macular split could be aggravated due to further stretching by abnormal vitreous body and epiretinal membrane, leading to loss of vision. The split might deteriorate into macular holes (Photo 3A) and even macular retinal detachment if left untreated. With OCT, it can now be detected and diagnosed in its early stage with high accuracy(Photo 3B). The treatment is pars plana vitrectomy with removal of the posterior hyaloid, epiretinal membrane and internal limiting membrane followed by gas injection. They can resolve maculoschisis in most patients. Most patients are not required to maintain a face down posture post-operatively.

maculopathy maculopathy
Photo 3: Optical Coherence Tomography(OCT): (A)extensive macular split, macular detachment and loss of macular depressions are detected under OCT before surgery (arrow) (B)Macular split improves significantly 6 months after surgery.

Treatment of Neovascular Membrenes caused by Age-Related (Photo 4) and Severe Myopic (Photo 5) Macular Degeneration
Photodynamic therapy was once the standard treatment of neovascular membrene caused by age-related and severe myopia macular degeneration. It has a limited effect of maintaining the remaining vision or deterring vision loss. Currently, intraocular injection(incl. Lucentis, Avastin, Eylea and steroids)is the common practice. It can restore vision to a certain extent in most patients. The procedure is safe. Side effects are rare.

maculopathy
Photo 4:Age-related macular degeneration - bleeding
maculopathy
Photo 5:Severe myopia macular degeneration


Diabetic Retinopathy

Diabetic Retinopathy
Currently, around 10 to 15% of the adult population in Hong Kong suffers from diabetes mellitus (DM). The age of onset is getting younger in recent years. DM can affect multiple organs in the body including the eyes. It can cause diabetic retinopathy, cataract, glaucoma and retinal detachment. Depending on the duration and age of onset of DM, the incidence of diabetic retinopathy varies from 20 to 55%.


Signs and Symptoms
Early diabetic retinopathy is asymptomatic and patients enjoy normal vision without redness and pain in the eyes. However, blood vessels would dilate, leak serum and phospholipids and form microaneurysms in the retina. Retinal capillaries closure will then cause ischemia and lead to the growth of new blood vessels. These new blood vessels bleed into vitreous cavity easily. Patients would experience sudden onset of floaters or even sudden blindness.

Normal Retina Retinal hemorrhages, cotton
wool spots and laser scars
Retinal detachment Vitreous hemorrhage


Examination and Prevention of Complication
Once DM is diagnosed, patients must regulate their diet, improve their life style and control their blood sugar with medications. Eye doctors should be consulted and a thorough examination of retina should be arranged. Fundus fluorescein angiography and laser treatment can be done to improve vision when necessary. Regular eye examination is recommended every six months to one year. More frequent follow-up is necessary when the retinopathy progresses.


Latest Treatment
Regular eye examination by doctors and strict control of blood sugar, blood pressure and blood cholesterol are essential in protecting vision. When new blood vessels are detected, or when the maculae are threatened by edema and exudates, intravitreal injection of anti-VEGF or laser photocoagulation can improve vision. In more severe conditions like retinal detachment, vitreous hemorrhage or refractory macular edema, vitrectomy is useful in restoring vision.

Macular edema

Laser treatment for diabetic retinopathy
Before Treatment After Treatment


Conclusion
Prevention is the best cure. Regular eye check up, strict blood sugar control and laser or surgical treatment can protect vision and prevent blindness for most diabetic patients.

Oculoplastic & Orbit Surgeries

Ophthalmic Plastic and Reconstructive Surgery is a subspecialty of Ophthalmology where Opthalmologists undergo special training to perform Plastic and Reconstructive Surgery around the Eye and Orbital area. Reconstructive surgery involves reconstructing eyelid tissue deficiencies after excision of tumours or loss of tissue from trauma, this also involve removal of orbital tumours, correcting thyroid related disorders such as Proptosis (protrusion of eye ball), eyelid retraction and also involve the reconstruction of the Naso Lacrimal System due to tumours or blockage and bony fractures around the orbit. .

Upper Eyelid Surgery
Cosmetic Eyelid Surgery is popular in Asia where a double lid crease is formed surgically for patients who have a single eyelid crease or on older patients where there is excessive skin over hanging the upper eyelid. In younger patients, the formation of upper lid crease gives the impression of the eye being larger. For older patients, where there is over hanging eyelid skin (Dermatochalasis), the excision of the skin and the reformation of the lid crease will give a much younger appearance to the patient. The patient will also have an increase in visual field if the extra skin is removed.

In younger patients, in order to form the extra lid crease, one can simply put in three temporary stitches (which may be removed later on) to bring the fold higher, this procedure requires less recovery time. However, this is less permanent than if a full incision was made on the upper eyelid skin and permanent stitches are placed to form the lid crease.


Lower Eyelid Surgery
Lower eyelid eye bags are caused by protrusion of fat, this gives the impression of the person looking aged and constantly tired. A new method of excising this fat and thus decreasing the eye bag is invented by ophthalmologists whereby one reaches the fat by entering the area between the eyelid and the eyeball. One simply makes small windows in this area behind the eyelid, pull out the fat and excise the fat using the CO2 Laser. The advantage of this approach, which is called 'Transconjunctival' approach, leaves no scar. The traditional approach through the eyelid skin can lead to a scar and also a risk of lid retraction, that is the lower lid being pulled down thus showing the white part of the eyeball. The Transconjunctival approach leaves minimal to no bruising at all whereas the traditional approach can leave the patient black and bruised for up to 3 weeks. Patient who have the surgery via the Transconjunctival approach only need to rest for 2 days and can return to work on the 3rd day. This fast recovery occurs for 2 reasons, first the CO2 Laser not only cuts fat but also stops bleeding, second, the Transconjunctival approach does not touch the skin or the muscle where 90% of bleeding occurs and there are no scars.


Before


A Day after Surgery:
No more lower eye bags.
No bruises and minimal swelling.

Neuro-Ophthalmology

Neuro-Ophthalmology is a sub-specialty in Ophthalmology and Neurology. It deals with neurological diseases that affect the visual function of the patient. Patients affected by certain neurological diseases may be manifested as visual blurring, loss of visual field, double vision, seeing things moving (oscillopsia), ptosis or pupil abnormality.

Common neuro-ophthalmological diseases include:
  • Ischaemic optic neuropathy (Non-arteritic or arteritic)
  • Compressive optic neuropathy due to orbital or brain tumours
  • Optic neuritis
  • Amaurosis fugax
  • Ocular myasthenia gravis
  • Ocular motor nerve palsy (Third, fourth and sixth cranial nerve palsy)
  • Essential blepharospasm / hemifacial spasm