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Pulastya Eye Clinic
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Eye Allergy

What is eye allergy?

Eye allergy is an abnormal response to any organic or chemical agent present in the air or somehow coming in contact with the eye. Red itchy watering eyes can often be due to eye allergy.
What causes it?
A person can develop allergy to just about any chemical or organic agent. Interestingly there can be allergy to even anti-allergy medicines.
The tendency for allergy is an inherent trait of a person and may have some genetic basis. People who are prone to allergies usually have multiple allergies.

Who are at risk?
Allergy is seen more commonly in children or young adults who have a hyperactive immune system. People borne of parents who have allergies are at greater risk and so are individuals living or working in environments where they are exposed to chemical fumes or organic dust.
Some specific types of eye allergies are more common in young boys aged 5 to 15 years viz. Vernal Catarrh or Conjunctivitis and some may occur in people who harbor some infections in the body.

What are the symptoms & signs?
Redness, itching & watering are typical symptoms of eye allergy. These symptoms may be accompanied by episodes of sneezing, slight fever, breathlessness or skin allergies. Occurrence of allergy is always preceded by exposure to allergen (the agent causing allergy), so it may be more common in a particular season or a particular environment. In Vernal Conjunctivitis the symptoms are more common in summer months and patient feels better in winter months.
The eyes appear red and may be slightly swollen. Prolonged recurrent allergy can lead to dropping of upper eyelids giving a sleepy appearance. There can be stringy or ropy discharge from the eye and there could be formation of a whitish ring on cornea (black of the eye).

The vision is usually not affected by allergy.

How is it diagnosed?
Eye allergy can be easily diagnosed by its symptoms and a typical history, and by detailed eye examination which reveals the characteristic signs. However, finding out the exact cause or agent giving rise to allergy may not be easy unless an observant patient is able to relate the symptoms to specific agent or one may have to conduct a battery of sensitivity tests with not so rewarding results.
What is the treatment?
The treatment may include some or all of the following depending on the severity of clinical situation:
Avoidance of the agent causing allergy or allergen – this is the single most important step in the management of allergy. But identifying and avoiding allergen may not always be possible. In such situations one has to wait for the allergy to die out on its own. At Pulastya eye clinic we also do special allergy testing to identify the specific allergen and then there is a vaccination programme for severe cases.
Anti-allergic eye drops and sometimes oral anti-allergic tablets.
Mast-cell Stabilizing drugs as eye drops are used to prevent recurrence of seasonal allergy.
Steroid eye drops may be required in severe cases as a short course to control the disease.
Desensitization is possible in some cases where a specific allergen can be identified and isolated.
What are the surgical options?
Surgery is rarely required for eye allergy. One of the indications for surgery is development of extremely large cauliflower papillae in severe cases of Vernal Conjunctivitis. These giant papillae may require removal / excision by surgery.
What are the outcomes?
Allergy usually dies out naturally over a period of 3-4 years; however, in some cases it may trouble lifelong. It can be easily controlled with use of appropriate drugs (but better under supervision).
What are the complications?
Complications caused by allergy itself are uncommon but are usually caused by the side-effects of the drugs used for its treatment. Prolonged use of steroids as required in very severe cases can lead to development of glaucoma and cataract. Vernal conjunctivitis cases can develop dropping of eyelids (Ptosis) and a ring like opacity in peripheral cornea  (Cupid ’s bow).
What is the time course?
In majority of cases the allergy can be easily controlled in 1-2 weeks time. But drug treatment may be required for a few weeks to months to maintain a certain level of comfort. In most cases the allergy lasts 3-4 years.
 
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 Contact Lenses
A contact lens is a thin lens placed directly on the surface of the eye...
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 Refractive Errors
The rays of light are focused on the retina - the light sensitive layer of the eye...
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 Eye Allergy
Eye allergy is an abnormal response to any organic or chemical agent...
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 Cataract Surgery
Human eye has a natural lens which is normally transparent...
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Dr. Pooja Mehta
MBBS, DNB , MNAMS
+91-9818459728
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Intraocular Lenses (IOLs)
Intra-ocular Lenses (IOL) are small, made of a soft polymer (Acrylic) and are implanted inside the eye in place of natural lens.

Foldable IOLS: Made of either Silicon or Soft Acrylic. On folding, its diameter is reduced to 2.75 mm and it can be introduced into the eye through a 3 mm incision, where it unfolds automatically to take its position. The main advantage of this lens is that there is fast visual recovery in the patient.

Non-foldable Lens: This lens has a diameter of 5.5 mm. A 3 mm incision has to be enlarged to 5.5 mm to introduce this lens. However, the incision still remains self-sealing and requires no sutures in most of the cases.

Aberration Free Foldable Lens: This lens is like a foldable lens in all ways, except that it’s an aspheric lens. It reduces glare in the patient and is very useful for the patients who would like to drive at night.

Multifocal Lens: This is also a type of foldable lens which has distance as well as the near power in it. After its implantation, patients will become much less dependent on glasses for near as well as distance. However, if you have cylindrical power in your glasses, you may need corrective lenses for fine work.

The greatest advantage of IOL is a clear wide field of vision and the fact that the patient does not have to constantly wear thick glasses. Since the IOL stays in the eye lifelong therefore there should not be any compromise on the quality of the IOL. Multifocal IOLs offer the advantage clear distant and near vision and, thus, lesser dependence on glasses but suffer the disadvantage of lower contrast, lower color saturation and a subjective compromise in image quality. But both eyes have to be operated within short interval of 2-6 weeks and it takes about 4-8 weeks for complete adaptation to new visual status.

To conclude, the surgeon, the surgical technique and the quality of the IOL are not the only factors that decide the result of cataract surgery; but also the condition of the eye otherwise, the cornea, the retina and the presence of systemic diseases like diabetes, hypertension, asthma, infections, etc. Moreover, the quality of the operation theatres, the ancillary and the backup facilities, the training of the support staff, etc. also have a significant influence on the success of the surgery. Ensuring good quality in all these areas leads to increase in the surgical cost for the patient, but it must be understood that our eyes are worth a lot more...

 
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Cataract Surgery
The operations done for cataract are the following (the list includes only established standard procedures):

Phacoemulsification / MICS with Foldable Lens (Intraocular Lens - IOL)

Small Incision Cataract Surgery (SICS) with Foldable Intra-ocular Lens (IOL) Implantation.

Conventional surgery is virtually obsolete (but has to done in select cases)

 

Phacoemulsification
In Phacoemulsification a very small incision (3 mm or less) is made into the clear part of the eye (Cornea) and the hard core (nucleus) of the lens is converted in to a soft pulp using high frequency sound waves (NOT Laser) and sucked out. Then a foldable lens (IOL) is injected through the small incision and positioned into capsular bag. The main advantages of this operation are early rehabilitation and decreased occurrence of astigmatism (cylindrical power in glasses) & other complications. Non-foldable IOLs are not recommended as they necessitate enlarging the incision and thereby sacrificing the advantages of the small incision.

All these operations can be done under topical anesthesia (or eye drop anesthesia) which makes the eye numb/senseless, and the patient although conscious does not feel any pain. This removes the phobia of undereye injection (but rarely one does need to use injection anesthesia). The general anesthesia, which has its own risks, is used only in children and uncooperative patients. Topical or eye drops anesthesia is the preferred method as not only the painful injections and the eye bandage are avoided but it also reduces the risk associated with injection anesthesia (e.g., retro-bulbar hemorrhage, globe perforations, etc.)

 

Microincision Cataract Surgery (MICS)
MICS (Micro Incision Cataract Surgery) is just a variation of Phacoemulsification. Here using thinner phacoemulsification tips, the surgery is performed through narrower incision (about 2 mm). It offers only minimal advantage over standard phacoemulsification by causing slightly lesser surgical induced astigmatism. However, the IOLs implanted through such small incisions are still very new and the experience with them is very limited.

Lasers are not used to remove cataract (although some patients mistakenly use the term Laser for Phacoemulsification).

Is this technique more expensive than conventional stitch technique?
Hi-tech expensive equipment and special foldable lens are required to execute a good surgery, making it a little more expensive than the conventional technique.
Can an immature cataract be operated by Phaco?
It is easier and safer to operate on an immature cataract by Phaco. As the cataract matures, it tends to become harder requiring more Phaco energy to do the same job. Beyond a certain limit, excess energy may cause harm to the eye.
If one eye has had a conventional cataract surgery with IOL, can Phaco be done in the other eye?
Yes
 

Small Incision Cataract Surgery (SICS)
SICS (Small Incision Cataract Surgery) has virtually replaced the conventional cataract surgery for difficult situations. Here although the incision made is larger (5-6 mm) and the nucleus is removed using fluid pressure, yet no stitches are required and the recovery is much faster and more comfortable than the conventional surgery.

 
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Femtosecond Laser
Femtosecond Laseror Intralase for Creating Flap ("No Blade" or Blade Free Lasik)

Femtosecond Laser is a new method of creating corneal flap in Lasik - here instead of Microkeratome "Blade" or Disposable Microkeratome Head, a Laser is used to cut the corneal flap. Although it is touted as "No Blade" technique but that should not mean that there is no cutting of cornea to make a flap. The advantage is that the flap reproduceability is better i.e. there is less variation in flap thickness from patient to patient. This variation is slightly more in Disposable Microkeratome Head and significantly more with Reusable Heads & Blades. However, there are reports of increased risk of complications like DLK (Diffuse Lamellar Keratitis or Sands of Sahara) caused by disintegration of corneal tissue & collateral damage. The newer ultrathin 90 micron disposable microkeratome heads offer all the advantages of Femtosecond Laser without an increase risk of DLK. All these are relevant in thin corneas or high refractive errors where one is working close to the limits of safety.

Time Involved

An optimal time schedule is as follows:

Day 1 - Detailed eye examination (2 hours)
Day 2 or 3 - Lasik Surgery (3-4 hours in the center / hospital)
Actual time for Lasik is just few minutes!
Discussion: Standard Lasik vs. Custom Lasik

Standard Lasik
This is the conventional type of Lasik Laser where only the refractive error (myopia, astigmatism or hypermetropia) is taken into account in the Laser protocol and corrected. It does not correct aberrations (finer optical defects in the eye).

Custom Lasik
In this Lasik treatment in addition to refractive error, finer optical aberrations are also taken into account. The Laser ablation protocol attempts to correct the aberrations as well.
The information about the aberrations in the eye is provided by an instrument called aberrometer which forms an additional link in the treatment chain.

Which is better & why?
High levels of aberrations in the eye adversely affect contrast and night / low light vision. So if aberration level is high then certainly Custom Lasik is better as it provide better quality of vision, better contrast and better night vision by correction of aberrations along with the refractive errors.
It may be noted that the vision in bright day light is the same after both forms of Lasik (standard or custom) and it's only in mesopic or low light conditions that there is a difference in the quality of vision. And the difference is very subtle & mild - not a dramatic difference

Conclusion
LASIK is major advance in the field of refractive surgery, which combines efficacy, safety, precision and accuracy. This technique is taking us on the path that, in the past, ophthalmologists feared to tread, towards the goal of unaided natural clear vision. However, it is prudent to have realistic expectations from this surgery and never hope for miracles (although results of Lasik are no less!).
Lasik involves extensive computer analysis of the eye. Patient is then asked to come on the scheduled day for the laser treatment. Local anaesthetic eye drops are instilled in the eye to achieve a pain free procedure. The patient is now made to lie under the laser machine and asked to fix his gaze at a blinking light. The data of the patient is fed into the computer memory of the laser. A special machine called the microkeratome is used to pick up a thin corneal flap of 160 microns (equivalent to an onion skin). Laser is delivered to the cornea under this flap to correct the spectacle number. It takes 20 to 60 seconds to complete the laser delivery to one eye. The corneal flap is placed back in position where it holds strongly within two minutes due to its natural bonding properties. The entire procedure takes about 10 minutes.
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Lasik
Lasik is currently the best method of correction of refractive errors. It is accurate, effective and safe.

In LASIK an ultra-thin (90 to 150 micron) flap of cornea is raised and then using computer guided Excimer Laser (mostly Argon Fluoride 193 nm) is delivered to reshape the corneal stroma into predetermined curvature. The flap is repositioned back. This leads to correction of myopia, hypermetropia, and astigmatism. The procedure is short and simple and being computer controlled is highly accurate.

Patient Selection for Lasik
Case selection is an extremely important determinant of the results of Lasik surgery:
Refractive error:  -1.50  to -10.0 diopter of myopia
Up to +6.0 diopter hypermetropia
Astigmatism of up to 6 diopter
Minimum age 18 to 21 years (preferably 21 years)
Refraction should have been stable for at least a year.
Contraindications: Keratoconus, thin corneas, corneal inflammatory diseases, herpetic keratitis and autoimmune diseases.
Should not be performed during pregnancy - can be done 3 months after it.
Preoperative Preparation for Lasik
Refraction under cycloplegia
Corneal Topography
Pachymetry for corneal thickness
Aberrometry to measure higher order optical aberrations
Pupillometry to measure pupil size in low light conditions
Intra-Ocular Pressure (IOP) measurement
Detailed Retina Examination
Informed consent
Antibiotic eye drops to be instilled for about 2-5 days before surgery
Contact Lenses should be discontinued for at least 2 weeks (Soft Lenses) / 4 weeks (Rigid Lenses) before the surgery

Lasik Procedure
LASIK is performed under topical anesthesia (Proparacaine Eye Drops) and the only cooperation required of the patient is to fixate at a blinking (green) light. Current LASIK machines have an advanced eye tracker device which realigns the Laser to any changes in the position of the eye thereby ensuring proper centration of ablation. The steps are:

Lasik - Flap lifting
Excimer Laser ablates the stromal bed to resurface it into desired curvature. What makes the Excimer laser so well suited for corneal ablation is its ability to remove tissue with accuracy up to 0.25 micron with each pulse. Often, only 50 microns of tissue are removed to achieve the proper amount of correction. The Excimer produces a non-thermal light beam that eliminates the possibility of thermal damage to surrounding tissues. In current Lasers employing flying spot technology a 1 mm spot ablates the tissue to correct the refractive error and to blend this area with surrounding cornea by creating smooth transition zones.

During this step a clicking / crackling sound is heard and an odor of ablating tissue (similar to charring hair) is smelt and a light flashing close to the eye is seen. All this while patient needs to concentrate on the center of the blinking (target) spot of light.

Lasik - Laser Ablation
The corneal flap is then repositioned and allowed to dry for a few minutes. The flap self-seals without the need of sutures.

Antibiotic drops are instilled and the patient is discharged from the hospital. The patient is advised to report back the next day. Eye drops are prescribed to be started on the same day. Analgesics are rarely required and that too for 1-2 days.

Precautions to be taken after Lasik
Avoid swimming and splashing of water on the eyes for a month.
Avoid rubbing the eyes for a month.
Use sunglasses to avoid bright sun, dust, wind and air pollution.
Avoid excessive viewing of TV or computers for a week.
Use medicines regularly as advised.
Consult your eye surgeon in case of any problem
Avoid eye makeup for 1-2 weeks
Complications of Lasik
No surgical procedure is without any complications. However, LASIK is a relatively safe technique of correction of refractive errors. The possible complications can be:

Dry Eye
Under or over correction
Glare
Decentration of ablation
Astigmatism
Flap damage
Infection
Corneal infiltration
Diffuse Lamellar Keratitis (DLK or Sands of Sahara)
Corneal Ectasia (Keratoconus)
Results of Lasik
Results are generally very satisfactory and it has been reported that in carefully selected cases more than 90 % achieve unaided visual acuity of 6/12 or better (i.e., 6/12 6/9 6/6 6/5).

It is important to discuss with your surgeon about the expected results or prognosis in your case. Your surgeon will be able to explain the kind of results or problems likely in your case. A detailed discussion helps a lot in preparation for Lasik.
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