AN OPTOMETRIST
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Being usual for me to take questions from my patients and reply them convincingly I’ve covered the FAQ (s) from minus power (myopia), Increasing minus power (progressive myopia), plus power (hyperopia), cylinder power (astigmatism), spectacle lens, lazy eye (amblyopia), pink eye (conjunctivitis), corneal abnormality & disease, cataract and glaucoma.Trying to brief the useful ones lucidly and in simplest terms here with the help of schematic diagrams.
Consider that you are standing on the left (as shown in the diagram) and facing towards your friend’s eye. The visible part of his/her eye is cornea at the front, lens (invisible) in the middle and retina (invisible) in the back.
Cornea is transparent with no blood vessels. Helps in bending the light rays to the eye lens.
Lens is another transparent structure with highest light bending ability towards retina. It is made of natural fibres.
Retina is the screen of the eye onto which the light rays are focused to create a sharp and defined image. It is rich in blood supply through vessels.
‘F’ is the point on retina where rays must fall for perceiving a clear image as shown below in the schematic diagram.
‘DS & DC’ where ‘D’ stands for Dioptre, the unit of measuring lens power, ‘S’ represents the spherical component and ‘C’ denotes the cylindrical component of the lens power.
MINUS POWER (MYOPIA) (SHORTSIGHTEDNESS)
Light rays coming from far are focused somewhere in between the lens and retina as shown below in the schematic diagram.
Q1. Will my -5.00 DS power come down if I wear my spectacle regularly? (Student 22 YO)
A1. Firstly, you won’t be able to see clearly without wearing spectacle or contact lens. Spectacles are safer. Coming to your question, no it won’t come down under normal conditions. I am yet to come across such a case!
Q2. I spend a lot of time on screen and developed a power of -3.50 DS in my eyes over 2 years. Will it come down? (Student 21 YO)
A2. I suggest a follow-up every 6 months, in the meantime kindly reduce the screentime considerably. I need to check if there’s any change, usually should not progress. It’s time for it to stabilise, still let’s meet after 6 months.
Q3. Can my child’s -3.00 DS be stopped from growing further? (Child 10 YO)
A3. Possibly yes, but you need to be prompt.
Q4. Is myopia dangerous? (Student 19 YO)
A4. No. It’s progression beyond a certain limit surely raises concern for the visual health that can act as a trigger for serious irreversible eye conditions like glaucoma, posterior sub-capsular cataract, nuclear cataract, retinal detachment & myopic macular degeneration.
Q5. Can I start my treatment for containing myopic progression at 16?
A5. Yes, sooner the better. You can get treated for limiting its growth.
MINUS POWER INCREASING EVERY YEAR (PROGRESSIVE MYOPIA)
A condition where the focal point keeps on changing with respect to point ‘F’ on the retina & time (long durations, generally couple of months extending to a year or two) primarily due to elongation of the eyeball. Can be perceived as shifting of the focal point inwards and away from retina with respect to durations .… learn more
Q1. I and my husband are worried about the increasing minus power of our 12-years-old son. We want to know if this can be stopped and reversed.
A1. Yes, there are treatments to stop the increase depending on the cause. If the growth in power is due to elongation (increasing horizontal distance between cornea and retina) of the eyeball (apart from other health conditions/ pathological cause) the trigger to which is purely the myopic blur, it may be curbed. Reversal is a question of far and hardly such case has been recorded so far.
Q2. Can you please elaborate on the treatment methods for containing the growth of this minus power.
A2. Today’s fast paced dynamic lifestyle for kids demand too much of near work. Their visual activity has been limited to studies, use of mobile and laptops and others those are mostly confined to indoor activities. Eyes get less chance to relax. For such space bound activity culture, it is quite common that we take care of their visual needs. We’ve spectacle lenses and contact lenses too in different designs that take care of their vision while looking at far & near in such a way that the near vision status is continued without getting changed over passage of good period of time. It is the desire and simultaneous inability of the human bio- imaging system to focus clearly especially at near target that triggers (one of the trigger factor) the process of elongation. This theory has been actualised in practice while producing such special lenses, while there’s another principle that works on externally supporting the needed elasticity of the eye lens and inward turning to focus at nearby .… learn more
The schematic diagram shown below would help you to understand the design principles better.
The lens technologies to control myopic progression being used today are enlisted below:
a) Caring Accommodative Lag
b) DIMS (Defocus Incorporated Multiple Segments)
c) H.A.L.T (Highly Spherical Lenslet Target)
… learn more
BLUE RAY GUARD LENS AND ARC LENS
390 – 440 Nanometers is the wavelength band of visible violet and partially the indigo part of the blue colour in spectrum. This is the High Energy Visible (HEV) part in the visible spectrum. Lenses that don’t allow this spectrum of light to pass through are blue ray guard lenses as shown below in the schematic diagram. Anti-reflection coatings (metal oxide coatings) over the lens surfaces are done to minimize reflections from the front and back surface of the lens. These reflections are one of the causes of glare that reduce the quality of image. Upon removal of such reflections observing the principles of destructive interference, the quantum of light passing through the spectacle lens increases. Refer to the schematic diagram for clarity.
Q1. Is anti-reflection coated lens the best choice as I work on screen for more than 8 hours a day?
A1. You may opt for better class of protective lenses for your needs. I recommend blue ray guard lens that would limit the HEV light (390-440 nms) to enter your eyes. Mostly emitted from screens of laptop and mobiles, LEDs and even sun it would help eyes get strained lesser. Often boosted with anti-reflection coating over it, for enhanced clarity (explained above in the diagram) and reduced glare. Lenses with ARC now-a-days come with standard hydrophobic (water repelling) & oleophobic (oil repelling that causes a smudge free surface) treatments over the exposed surface. Dust repelling and anti-fog coatings can be added, if needed.
Q2. What is the benefit of using this blue ray guard lens?
A2. Blue ray guard lens limits the HEV light (390-440 nms) to enter your eyes. There’s a dual theory working behind it: it has pros & cons, both combined and present simultaneously.
Counting Pros:
a) These light help in maintaining sleep-wake cycle (circadian rhythm)
b) Keeps the memory good
c) Mood upliftment
Dealing Cons:
a) Macular Degeneration
b) Eye strain
c) Increased risk after cataract surgery
Q3. Are the lenses coated or the lens material is as such that it stops the blue rays?
A3. 3 Classes are available in production process. 1) Surface Coatings 2) Filter Substrates being placed 3) Melanin infused ophthalmic lens materials (highest filtering capacity).
PLUS POWER (HYPEROPIA)(HYPERMETROPIA)(FAR/LONG-SIGHTEDNESS)
Light rays coming from far are focused behind retina as shown below in the schematic diagram.
Q1. My kid (11 YO) has plus power. Can it be corrected.
A1. No worries, will get corrected in a controlled manner with the use of spectacle.
Q2. How could my daughter’s (14 YO) minus power be detected to be the plus power originally?
A2. It was a plus power right from the beginning and was wrongly diagnosed as minus power.
… learn more
Q3. Does my daughter (14 YO) really need to wear spectacles? I’ve heard that plus power comes down and gets corrected by itself.
A3. Yes, she must wear the correctional lenses to keep a check on the pace of self-correction and control on the lens focusing abilities.
… learn more
CYLINDER POWER (CYLINDRICAL POWER COMPONENTS) (ASTIGMATISM)
Rays coming from far get focused differently, fail to converge at a ‘point’ and tend to fall in ‘line’.Due to curvature differences, only two of the meridians 90 degrees apart can focus, rest of the meridians can’t. Hence only those two meridians are corrected for producing ‘point focus’ on retina.
Refer to the schematic diagram shown below for better understanding.
Q1. Is it a matter of concern for me to have two different powers in my one eye? (18 YO)
A1. Not really unless these powers continue to grow over shorter period of time.
Q2. Can the cylindrical component of my son (13 YO), get corrected? Will he squeeze to see better anymore?
A2. You’ve lot of time. Small correctional cylindrical power usually gets corrected by itself in cases of children. Once corrected for astigmatism, he won’t squeeze his eyes for clarity.
Q3. Would this high cylinder of -2.50 DC affect my vision in future? Would a jump from -0.75 DC to – 2.50 DC bring harm?
A3. It won’t if prescribed in controlled manner. Detected -2.50 DC. Prescribing a much lower value right now. Get back after a month for another round of visual assessment and prescription.
PROGRESSIVE LENS (PROGRESSIVE ADDITION LENS, PAL)
Lenses with no bifocal segments (moon shaped or inverted ‘D’ shaped or horizontal line across the lens dividing it in two vertical parts one above the other), that has a continuous surface for viewing the distance, intermediate as well as at the near. Refer to the schematic diagram as shown below:
Q1. Which of the brand for my new progressive lens would be better?
A1. It is not about the brand, it is all about the design. Any upgraded design from what you have been wearing would be better. Else, you can stick to the previous design. Degrading the design is not recommended from my part.
Q2. What’s free-form lens?
A2. Optimally (Either general or Customised) designed lens surfaces fall in free-form category. These designs are better in terms of distortion areas and mechanical aspects those are impractical to be taken care of in traditional or conventional designs. Precision of such a design can be had upto 0.01D. Basically, all the coined names like ‘digital’, ‘HD’, ‘cut-to-polish’ by various manufacturing and processing concerns represent the same lens technology!
… learn more
LAZY EYE (AMBLYOPIA)
One of the eyes can see fairly and markedly less than the other.
Q1. How to get my child’s one eye that sees less get treated?
A1. Such a condition is called a lazy eye. There are many modes of treatment available now-a-days. You need to have the following prior to take the course of treatment:
a) Strong urge for the treatment
b) Patience while your child undergoes the treatment. Discontinuation wouldn’t yield.
c) Time for attentively monitoring your child.
d) Cost of treatment is a factor in some modes & not in others, depending upon the cause and factors being responsible for the condition.
Q2. Can I start the treatment for my child’s lazy eye now?
A2. Yes, sooner the better.
Q3. At 21 (years old), is it possible to treat my lazy eye?
A3. Since you’re not strabismic, the chances for improvement are higher. You can go for it.
Q4. How long would the treatment for lazy eye continue?
A4. Generally ranging from a couple of months to 24 months, at best.
Q5. Does the lazy eye come back after being treated?
A5. Not often. But it might. A periodic routine vision check-up is essential.
Q6. What if while undergoing the treatment for one of my eyes, the other eye gets lazy?
A6. Yes, it may. That’s why a short periodic visual evaluation for both of eyes is being prescribed.
Q7. Could you please enlist the consequences for untreated lazy eye?
A7. Consequences could be numerous, like
a) Poor depth perception
b) Continued visual loss in the lazy eye
c) What if your good eye is injured or catches disease in some way? You shall be left with the
lazy eye only and the whole sight would be badly affected!
CATARACT
Hardening of the natural eye lens fibres resulting in loss of transparency and hence reducing visibility that is otherwise soft and transparent under normal natural health conditions. May result in blindness if left untreated. Refer to the schematic diagram as shown below:
Q 1. When shall be it right to remove the cataract from my eye?
A 1. Sooner the better, else by the time it hinders your regular work due to poor visibility even after wearing spectacle.
Q2. Can cataract develop again?
A2. No, it doesn’t. But ‘secondary cataract’ may develop in the posterior (back) capsule of the operated eye. This capsule is left behind to support the artificial lens. The procedure known as YAG Laser Capsulotomy is achieved by treating through laser for removal of this opacified capsule and takes nearly 15 minutes.
Q3. How long would it take to recover after cataract surgery?
A3. Usually 1-2 weeks, to be judged by the expert.
Q4. How soon can I resume my daily work after cataract surgery?
A4. Usually after 72 hours to 10 days, with full precautions as prescribed and advised by the surgeon.
PINK EYE (CONJUNCTIVITIS)
Disease characterized by redness, itching, watering, discharge, mucous type discharge, formation of crusts. Few or more characteristics as mentioned are presented together. Usually, no serious consequences involved.
Q1. How long does a pink eye take to recover?
A1. 4-5 Days for characteristics of bacterial and allergic origin and around 10-15 days for viral ones
that might extend up to 21 days in some cases.
Q2. Would the pink eye have effect over my vision.
A2. Unusual.
Q3. Would the pink eye recur?
A3. Yes, it might.
CORNEAL ABNORMALITY & DISEASE
Abnormal scratches, scars and diseases in cornea. Serious consequences related to sight might be involved if left untreated.
Q1. Will the scratch mark over my cornea heal?
A1. Yes, under treatment the cornea usually heals up within a few days. No signs of scratch mark are left.
Q2. How long would my keratitis take to go?
A2. Usually, signs would start slowing down after 24 to 48 hours of treatment and would take a few days to recover.
Q3. Can the ulcer over my cornea have severe consequence?
A3. Yes, it may lead to cataract if left untreated. You must visit a corneal expert on this.
Q4. How to remove the old scar mark over my cornea?
A4. You’ve to seek surgical intervention. Depending on it’s physical aspects, treatments with laser, corneal transplant & artificial corneal treatments are available. You need to seek the corneal expert’s opinion on this.
GLAUCOMA
Group of abnormal conditions or diseases in which the nerve connecting the eyeball to the brain is slowly damaged and the vision is affected and limited from side-views (while looking straight) to central-straight over passage of time if left untreated for long. May result in blindness if left untreated.
Q1. Why do you suggest for other diagnostic tests and visit to glaucoma expert even if I’ve a normal eye pressure?
A1. I am trying to rule out the possibility of glaucoma that occurs even after having normal eye pressure (Normal Tension Glaucoma) in which the optic nerve is damaged. This is the case where the vision constricts from periphery to centre, without producing any signs.
Q2. Will I get my vision back, if that’s lost due to glaucoma?
A2. Unfortunately, not. But upon continuation of proper treatment under the expert’s purview, the damage to sight can be restricted.
Thank You.
