Updated: Sep 29, 2021
Lot many patients with #Keratoconus or other #irregular corneal conditions like #Pellucid Marginal degeneration or Surgery induced Corneal Irregularity have been enquiring for mini scleral lenses thinking a small diameter lens will be easier to wear and remove and better fit their pockets as well! But sometimes the mini sclerals may fit your pockets but may compromise your cornea. So the decision is based on many parameters. Let's see some of them!
Every irregular cornea (the black portion) is different. Certain cornea is steep only in the centre and flat in the periphery. Certain cornea is steep throughout. From the topography below it is imperative that the two corneas are different in area of steepening.
The red shade shows the steepening and greener and bluer shades show flatter area of cornea. You may imagine like a mountain with crest and trough . The scleral lens should be fitted in such a way that the lens vaults the entire cornea filling the spaces with fluid to form regular surface so that the light entering the eye will not get scattered.
That being said, the #scleral lens doesn't touch the cornea. It lands only on sclera, the white portion. There is one more important part of eye between cornea and sclera called limbus which generates stem cells for the corneal rejuvenation. So its essential that the #Scleral lens should not land over the limbal zone as it would disturb the corneal health.
The sclera (the white portion) is asymmetrical in nature and has numerous blood vessels. There can be irregularities over sclera as well. The #scleral lens diameter will be chosen in such a way that it doesn't disturb or irritate the irregularities of sclera as well!
Therefore the diameter of the lens depends upon the type of corneal irregularity and
the size of the black portion, limbal zone and irregularities present in sclera. To achieve the best fit diameter of the lens plays a crucial role. What is mini scleral for one patient may be a scleral lens for the other patient.
Yes.. It's easy to wear and remove a small diameter lens than a larger one. I generally prefer to give minimum diameter lens which doesn't compromise the health of the cornea. My decision also depends upon age of the patient, the eye hand co-ordination and etc,. We can get well trained in wearing and removing of lens with practice.
Its always better to leave the selection of diameter to the practitioner to tailor the lens according to the eye's parameters rather than going in for mini scleral or scleral based on the ease of handling and cost as major considerations. Because we are dealing with compromised corneas when we talk about scleral lens! The health and transparency of the cornea is based on the hydration of Cornea and healthy limbus. In fact, the term Mini Scleral is not applicable nowadays. The lens landing on sclera is a scleral lens irrespective of the diameter of lens!
The diameter selection of scleral lens plays a major role in giving best fit lens. The diameter will be chosen by the scleral lens expert considering age, corneal irregularity, scleral irregularity, size of cornea so as not to compromise limbal stem cell zone, ease of handling (eye hand co-ordination) and etc,.Your Scleral lens Consultant will examine all the above mentioned factors before tailoring a #scleral lens for you! If you have further queries regarding right lens for your irregular cornea, don't hesitate to visit us @ eyefuloptometryclinic.com or you shall mail us at email@example.com