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MS, DNB, FRCS (Glasg.) FAICO (Glaucoma)
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You should be at least 18 years old to undergo LASIK surgery.You need to get your eyes checked by an ophthalmologist to know whether LASIK is suitable for your eyes. This includes assessment of stabilty of glass prescription over last 18 month, dry eye status, corneal topography and thickness and retinal evaluation. If the test results are favourable, then LASIK can be done. If LASIK is not suitable, phakic IOL (ICL) can be considered if your eye is suitable.
Spectacle power is expressed in Dioptres in plus or minus form. Minus spectacle lens indicates myopia. Spectacle prescription also carries a column called visual acuity (VA) which is the expression of amount of vision you have. Normal visual acuity is expressed as 6/6 or 20/20.
If you want to know the power of the contact lens for a given spectacle number, it is same as spectacle power prescription of less than -4.0D. There is a correction factor ( higher power) required for prescription above -4.0D. In your case for a prescription of -3.5D spectacle and contact lens prescription would be the same.
If you do not want to undergo surgery and wear glasses, you can wear a special type of contact lens called Ortho K contact lens for few hours. The effect of this contact lens lasts for many hours after removing contact lens. However it is required to continue to wear ortho K contact lenses for few hours in a day. This is useful for myopia of mild to moderate degree.
It is possible to get your spectacle number to zero with a prediction error of +/- 0.5D.This is possible now due to availability of good measurement instruments like optical biometers and latest IOL calculation formulae like Barett formula and Hill RBF formula which works on artificial intelligence You can plan near zero power for distance or you can plan to leave behind a planned minus number to allow you to have good reading without glasses when monofocal lens is planned. You can also plan a multifocal lens to get unaided( without glasses) good vision for distance and near.
Since you are 26 years old, it is very unlikely that your spectacle number would increase significantly in the coming years. Myopia increases till the age of 18 years and occasionally till 21 years due to increase in axial length of eyeball. If your spectacle glass power has not increased in last 1 or 2 years, it is very unlikely that your spectacle number would increase in future
Myopia is corrected by minus spectacle glasses. A simple minus powered glass is a concave lens. But in spectacle glasses a combination of plus lens surface ( front convex surface) and a minus lens surface ( back concave surface ) is used. This design of spectacle glass is called meniscus design. For example if you have to need a spectacle glass of -2 D then front surface will have a power has +6.0 D (referred to as base curve) and back surface of the lens will have a power of -8D . This design is created specifically to reduce spherical aberration and chromatic aberration induced by the spectacle glass. Base curve for different sets of glass power is different and is different for plus and minus lenses.
Eye glass power is normally checked by objective method ( retinoscopy or autorefractometer- computerised method) and later verified by subjective method ( by putting trial lens and asking you read the distance vision chart) to give you the exact prescription. However subjective verification of objective method is not possible in infants and very young children. Hence most of the glass prescription is based on objective method. Additional challenge in infants and children is the amount of accommodation the young eye is capable of. Accommodation is a process where in eye power is increased by changing the power of the lens inside the eye by the ciliary muscle while looking at near object. Since children have large accommodative power, the objective method of refraction( dry refraction) may be inaccurate. Hence a cycloplegia eye drops ( atropine, homoatropine or cyclopentolate) are instilled into the eye to temporarily paralyse the accommodation and check the accurate spectacle number. Occasionally this may need to be done under mild sedation. If the child has squint it is measured using prisms and appropriate correcting prisms are incorporated in the glasses in appropriate cases. Squints may be corrected by glasses, prisms or surgery depending on the type of squint.
Cataract surgery with intraocular lens(IOL)is one of the most common and one of the safest surgeries. With use of modern technology of phacoemulsification for cataract surgery and availability of foldable IOL, surgery can be performed in 10 minutes with a smallest self sealing incision(2.2MM sized incision) under local anaesthetic drops. There is no bandage put over the eye after surgery in most of the cases. Recovery is quick and the person will able to watch TV from the very next day of surgery.
Having said it is one of the safest surgery, it may be associated with small complications and occasional serious complications such as infection. Most of these can be prevented by taking adequate preoperative and postoperative care including instillation of eye drops and avoiding injury to the eye.
Monofocal IOL corrects spherical power for distance. If you have a cylindrical power due to corneal astigmatism toric monofocal IOL will give you good vision for distance without glasses. Monofocal aspheric design IOL corrects spherical aberration of the cornea gives good quality of vision for distance without glasses. You can opt for one of these monofocal IOLs depending on the recommendations of your eye surgeon after your complete eye examination. If you are willing to wear glasses for reading(near work) and computer work(intermediate distance), one of these monofocal IOL is the best option for you. Furthermore monofocal lenses have least night vision problems and hence suitable for people who require to drive at night frequently.
Brinzolamide and Brimonidine eye drops are anti glaucoma medication to control the eye pressure in glaucoma. Individually they can reduce the pressure by around 20%. How ever when used in combination its effect is lesser than the arithmetic sum of its individual efficacy. Both these drugs are considered second line medication as efficacy in terms of reducing the eye pressure is lesser than the first line drug. First line drugs for glaucoma are prostaglandin eye drops( Travaprost/ bimatoprost and Latanoprost) and beta blocker eye drops( Timolol). Prostaglandins can reduce the pressure upto 35% and beta blockers upto 25% when used independently. Hence first line drugs are preferred over second line drugs in the initial treatment of glaucoma unless there is a contraindication for the first line drug.
Antiglaucoma medications are used as a single medication or in combination depending on the amount of pressure required to be reduced in an individual patient. This depends on the initial eye pressure at diagnoses, age of the patient and the amount of optic nerve damage that has already happened.
Most of the multifocal and trifocal lenses work on diffractive technology. Here certain proportion of light from distance, intermediate and near are focussed simultaneously on the retina. In prepresbyopic aged patient( < 40 years), the normal crystalline lens changes its shape with the input received from the brain to focus on a particular distance. Hence at a time, it focusses 100 percent of light from distance or near or intermediate .This is not possible with artificial multifocal lens which cannot change its power to focus at a distance of interest at that particular time. Hence simultaneous focussing of multiple distances are done by diffractive multifocal technology. This allows only a part of the light to be focussed from a particular distance and light from multiple distance are focussed simultaneously. As a result the brightness of image and quality of vision ( contrast sensitivity is affected) in diffractive multifocal technology. Furthermore a small proportion of loss of light energy occurs in multifocal IOLs due to inherent property of diffractive multifocal lenses. This affects vision during dim illumination.
With few limitations in diffractive multifocal technology, it needs a perfectly functioning eye to give a good performance in multifocal IOLs. Any eye disease which limits quantity and quality of vision is a contraindication for multifocal IOL. Severe dry eye, irregular astigmatism, corneal opacity, large ange alpha and kappa, zonular weakness, any optic nerve disease including glaucoma and retinal diseases are medical contraindications for multifocal IOL.
Halos and glare associated with diffractive multifocal IOL can cause night driving problems. People who have to work in low illumination, drive frequently at night and looking for crisp vision are not suitable for multifocal IOL
Multifocal and trifocal IOLs are suitable for people who have a strong drive for not wearing glasses for reading as well as distance and vision and are willing to accept few limitations of the multifocal IOL. Hence eye surgeon does not suggest multifocal IOL to all the patients.
Squint ( deviation of the eye) is often associated with spectacle power. If inward deviation of the eye (esotropia) is associated with plus spectacle number ( hypermetropia), then squint is likely to be corrected by spectacle( accommodative esotropia). If outward deviation(exotropia) is associated with minus spectacle number then squint is likely to improve with the prescribed glasses. However the eye needs to be evaluated by the eye specialist to under what type of intermittent squint( occasional deviation of the eye). Certain types of squint improves with spectacle use. One needs to know whether it is a plus 3 spectacle number or minus 3 spectacle number and also whether it is inward or outward deviation of the eye. Furthermore complete orthoptic work up including assessment of AC/A ratio is required especially in inward deviation of the eye. Consult your eye specialist for detailed evaluation.
Postoperative infection is a rare but a serious complication after cataract surgery. It normally present with redness, pain and blurred vision. Most commonly it presents between 24hours to 36 hours after surgery. However low grade infection can begin after 3 months( late onset endophthalmitis).
ICL is a type of phakic IOL which is used in treatment of high refractive surgery. Eyes with low refractive error and good corneal topography are suitable for corneal laser refractive surgery ( LASIK, PRK and SMILE). Eyes with high refractive error and borderline or poor corneal topography are more suitable for ICL. There are certain prerequisites for phakic IOL as well. Eyes need to have good endothelial health and good anterior chamber depth to have implantation of ICL.
Advantages of ICL include
- Ability to correct high spectacle number ( upto -15D)
- No risk of corneal ectasia (unlike laser corneal laser refractive surgery)
- Reversibility of the procedure
- Better quality of night vision
- Does not pose a challenge to accurate IOL power calculation for future cataract surgery
Diadvantages of ICL
- It is an intraocular surgery and carries a small risk of intraocular infection like any other intraocular surgery
- There is small risk of cataract and increased intraocular pressure which are negligible with latest designs of ICL
You can become an ophthalmologist by doing post graduation in Ophthalmology after completing basic medical education(MBBS). Various post graduate courses in ophthalmology are MS( Master Of Surgery), DNB ( Diplomate in National Board) and DOMS( Post graduate Diploma in Ophthalmology)