CONTACT LENSES

Contact Lenses are prescribed in four main types of cases:-

(1) Pathological eyes, e.g. corneal scars
Keratoconus

(2) High refractive errors - high myopes, aphakes: better visual field than
glasses, more natural vision.

(3) Cosmetic - in place of spectacles.

(4) Sport - especially for those involving physical contact or risks.

There are two main types of contact lenses:-
(i) Hard lenses - smaller than the cornea, made of rigid plastic. They
correct moderated amounts of astigmatism as well
as the spherical refractive error.

(ii) Soft lenses - almost the same size as the cornea or larger, made
up of soft plastic sponges containing 40% or more of
water. They correct the spherical errors but can correct
only little astigmatism, unless an astigmatic correction
is incorporated. Soft lenses are subject to infection so
must be sterilized.

Complications:
Corneal abrasions may develop due to ill fitting lenses, or to trauma during
insertion of the lenses. Conjunctivitis and/or Keratitis may occur if the
lens is contaminated. Giant papillary conjunctivitis from soft lenses. The
patient should be instructed to seek attention if undue lacrimation or undue
irritaion persists, or if conjunctival discharge is present. Therapeutic contact
lenses may be used to assist treatment of corneal disease.

Advantages of Contact Lenses:
1. Provide a wider field of view.
2. Move with the eyes so wearer is constantly looking through optical centre
of lens. Most important in higher powered lenses.
3. Eliminate nuisance of spectacle frames which either slip or rub.
4. Well suited to wet weather and steamy conditions where spectacles
become wet or foggy.
5. Can overcome astigmatism as in corneal scarring and conical corneas.
6. Aphakic patients may obtain better vision.
7. Medical conditions eg. scarred eyelids, chemical burns, can be aided
with lenses.

Disadvantages of Contact Lenses:
1. Hazards injury from badly fitting, badly fitted, bad hygiene.
2. TIME FACTOR - finding, fitting, cleansing, sterilizing, adjusting to wearing.

PTOSIS

Ptosis - drooping of the eyelid, may be congenital or acquired.

1. Congenital - genetic

Absent or poorly developed superior levator muscle; may be associated
weakness of the superior rectus. Also congenital iii nerve palsy.

2. Acquired

(a) Traumatic - direct muscle involvement.
(b) Inflammation - infections - of the eyelids, the forehead, the eye (intraocular)
or the orbit.
(c) Muscular - myasthenia gravis (tensilon test), myopathies, myotonia.
(d) Senile - myopathy, skin laxity, blepharochalasis.
(e) Neural - lesions of CIII - at the nucleus, in the cranium or in the orbit. Jaw
winking - upper eyelid lifts with chewing ( wrongly directed fibres
of CIII.
Sympathetic Paralysis Muiler's muscles - Horner's Syndrome.
(f) Tumours - neurofibromatosis, pressure on CIII.
(g) Vascular - aneurysms of the intracranial arteries - pressure on CIII.
(h) Functional - associated with photophobia or diplopia, hysterical.

Treatment - medical or surgical depending on the underlying cause. Surgery
by levator shortening or slings to the frontalis muscle.

Unilateral congenital ptosis needs urgent treatment if the pupil is converted,
otherwise severe amblyopia will occur.

Eyelid retration and lid lag
Thyroid eye disease
Overactivity of Muiler's muscle after ptosis operations.

ASTIGMATISM

Astigmatism is a refractive error in which light rays entering the eye are not
refracted uniformly in all directions. A point focus on the retina is not attained
and blurred vision results. Corneal astigmatism occurs when the radius of
curvature of the cornea is not equal in all directions.

1. Regular Astigmatism - occurs when the corneal curvature is uniformly
different in meridians at right angles to each other.

2. Irregular Astigmatism - occurs when the rays of light in different meridians
ar focused differently and without a pattern, especially if there is an asso-
ciated pathological condition of the cornea.
For example:
- developmental abnormality
- keratoconus
- corneal scars
- trauma
- inflammation

Treatment:
(a) Regular Astigmatism - a cylindrical lens bends the rays of light in one
meridian only, by combining it with a spherical lens, rays of light from
all the meridian can be focused on the retina. A cylindrical convex
lens is used for hypertropic contact lens may form a smooth evenly
curved artificial surface of the cornea and so can correct corneal
astigmatism.

(b) Irregular Astigmatism - cannot be completely corrected with spectacles.
It may be improved by hard contact lenses which ride over the irregular
parts of the cornea.

In more severe cases, penetrating keratoplasty (corneal graft) will be
required to replace the abnormal cornea.

Herpes Zoster Ophthalmicus

Herpes Zoster Ophthalmicus is due to a virus infection of the ophthalmic division of the
trigeminal nerve (CV). The virus is related to herpes virus varicella (Chicken pox).

Signs & Symptoms:
Appearance of vesicles strictly limited to one half of the forehead and spreading
the the tip of the nose if the naso-ciliary branch is involved.

Neuralgic pain may precede the rash by 24 to 48 hours.

Ocular Complications may include:
- red swollen eyelids
- ciliary injection
- oedema of cornea
- lowering of corneal sensation
- keratitis, localised lesion or complete bullous.
- uveitis
- secondary glaucoma
- episcleritis or scleritis
- optic neuritis
- ocular muscle paralysis

Treatment - This is directed towards protecting the cornea and preventing
secondary infections, and the use of drying antiseptics for the forehead.
If no signs of corneal involvement, local antibiotic drops to combat secondary
infection are sufficient.

If keratitis or uveitis follows then the use of Acyclovir eye ointment in
combination with topical steroids and mydriatics may be used under
ophthalmological supervision.

Analgesics are often requiered in large doses to relieve the neuralgia. There
may also be a place for the use of intravenous Acyclovir and high dose steroids
in the early stages to prevent the onset of neuralgia if the patient is seen early.

HERPES SIMPLEX KERATITIS

Herpes Simplex Keratitis is the most common corneal virus infection. It is caused by herpes
simplex virus and is manifest as a dendritic, (branching) staining figure in the corneal epithelium.
This is high-lighted by staining with Bengal Rose 1% which shows dead epithelial cells, or
Fluorescein 1% which stains breaks in the corneal epithelium.

Symptoms are:
- photophobia
- irritation
- lacrimation
- and blurred vision if the cornea is affected.
There is a tendency for dendritic ulcer to lead to a deep stromal type of keratitis known
as Disciform Keratitis. The grey central infiltration of the cornea is caused by antibody-antigen
reaction within the stromal layer of the cornea. Recurrences are common and iritis is frequent.
If the lesion becomes necrotic, hypopyon and perforation of the cornea may occur.

(i) Dendritic Ulcers
Treatment:
(a) Debridement - topical anaesthetic drops are instilled, and loose epithelium containing much
virus is wiped off.

(b) Antiviral Medication - several agents are currently available in this country -
(i) Idoxuridine (Stoxil, herplex)
(ii) Vidarabine (VIRA - A)
(iii) Acyclovir (Zovirax)

These drugs interfere with the growth of the herpes simplex virus, but often are toxic in their
effect to the cornea and should only be used for a short duration.

(c) Antibacterial Cover - a broad spectrum antibiotic eye drop may also be used.

(d) Mydriatic - drops to dilate the pupil may be used to prevent posterior synechiae which
may result because of the associated uveitis.

(e) Cycloplegic drops may also be used to immobilize the ciliary muscle and to rest the
eye and relieve pain.

(f) Sunglasses or eye pad may be required to diminish photophobia.

(ii) Disciform Herpetic Keratitis is usually an excessive immune reaction.
Steroids are administered to diminish this reaction, but they must be used under strict
medical supervision or they may lead to extensive ulceration or perforation of the cornea.
Treatment may be prolonged.

Possible Complications of Cataract Surgery

Any surgical procedure is associated with risks to the patient. While the ophthalmologist makes every attempt
to minimise risks, complications can occur that may be permanent effects.

When you are making the decision to have surgery, you may keep in mind that your ophthalmologist cannot
guarantee that the surgery will always be successful or that the surgery bears no risk. The operation and its
outcome might not meet your expectations.

It is not usual for a surgeon to outline every possible side effect or rare complication of a surgical procedure.
However, it is important that you have enough information about possible complications to fully weigh up the
benefits and risks of surgery. If one eye is blind (or has extremely poor vision), you must carefully weigh the
benefits against the risks of cataract surgery on your only "working" eye.

Serious complications following cataract extraction are not common because of the significant surgical advan-
ces in recent years. However, if complications do occur, vision may be impaired or even lost.

Some people with pre-existing syndromes are at greater risk, so be certain to give you ophthalmologist your
complete medical history. Smoking obesity and other significant medical problems can cause great risks of
complications.

The following possible complications are listed to inform you and not to alarm you. There may be other com-
plications that are not listed.

• Infection inside the eye.
• Bleeding and blood collection within the eye.
• Excessive inflammation.
• High pressure within the eye.
• Retained piece of cataract in the eye.
• Damage to, or dislocation of, the artificial lens.
• Detachment of the retina.
• Drooping eyelid.
• Swelling and clouding of the cornea.
• Rarely, blindness and loss of the operated eye. Rarely, the unoperated eye may become inflamed, with

partial or total loss of vision ("sympathetic ophthalmia").

• Further surgery (for example, removal of the lens implant).

Although most complications resolve following additional treatment and over time, they can affect vision, sometimes permanently.

Signs and Symptoms after Surgery

Be sure to tell your opthalmologist if you have any of the following signs or symptoms:

• fever more than 38'C
• chills
• increasing redness of the eye
• increasingly blurred or disturbed vision
• nausea or vomiting
• excessive coughing
• pain that is not relieved by non-prescription medications such as paracetamol
• any other concerns regarding your surgery.

Cloudy Vision after Surgery

Once the natural lens has been removed, a cataract cannot come back. However, in a few patients, vision after surgery may again become cloudy and hazy.

This is due to clouding of the lens capsule behind the intraocular lens. A cloudy capsule can take months or years to develop.

An ophthalmologist can quickly correct the problem. A laser beam is used to create an opening in the cloudy capsule which allows light to pass easily.

This procedure is called a capsulotomy. It is painless and safe, and results can be seen at once.

Complications can occur, but they are rare. If you need a capsulotomy, ask your ophthalmologist to discuss its benefits, risks and limitations.

Surgical Techniques for the Removal of Cataracts

Ophthalmologists use three different methods to remove a cataract.

1. Phacoemulsification: The most common surgical technique is phacoemulsification (pronounced "fay-ko-emul-sa-fah-kay-shun"). You may hear your ophthalmologist use this term.

Viewing the eye through a high-powered microscope placed above the patient, the ophthalmologist makes a three-millimetre incision at the junction where the cornea meets the sclera. A small probe, which vibrates at high frequencies, is inserted to divide the cloudy lens into small pieces. The pieces are gently suctioned away from the
lens capsule through the incision. Small instruments are used to remove lens fragments if they are difficult to remove.

The artificial lens is usually inserted into the lens capsule. However, in some cases, the artificial lens may have to be placed in front of the iris.

The incision is normally so small that it often requires no stitches, or perhaps only one or two. After surgery, the eye is covered with a shield for protection.

The operation usually takes from 20 to 60 minutes.

2. Extracapsular Cataract Extraction: This technique is used less commonly. It is effective for those patients whose lens nucleus is too hard to remove using phacoemulsification and suction.

The ophthalmologist makes a 10 to 12 millimetre incision at the border of the cornea and the sclera. The front of the capsule is opened, and the lens is removed. An intraocular lens is inserted and fixed in positioned. The incision is then closed with several sutures.

Inflammation caused by the procedure usually takes several days or weeks to settle down completely. Vision may remain hazy or cloudy during that time. Over the next three months, vision should slowly improve.

3. Intracapsular Extraction: The ophthalmologist removed the entire lens and lens capsule. This technique is rarely used and only in special cases.

Cataract Surgery on the Second Eye: If both lenses are affected by cataracts, your ophthalmologist will usually wait until the first eye has healed before operating on your second eye.

Pre-existing conditions: In some cases, pre-existing medical problems may interfere with the successful visual outcome that the patient was hoping for. For example, this may occur in people with glaucoma, macular degeneration or other serious eye conditions.

Even if the cataract surgery is successful in such patients, there is a possibility that vision will be improved only slightly or not at all.