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Anterior segment scans offer illuminating view


Andrew Huhtanen
Richard Lindsay
Richard Lindsay & Associates, Melbourne VIC

Nidek RS-3000 Advance OCT

Designs For Vision


The Nidek RS-3000 Advance OCT has been a wonderful addition to our practice. Among other things, it has been a fantastic aid for the speciality contact lens fittings, with the anterior segment scans assisting greatly in the assessment of miniscleral and hybrid lenses on the eye.

Anterior segment scans

In the course of fitting many patients with interesting and irregular corneae, we realised that the anterior segment scans gave us a wonderful view of the corneal profile which in turn we could show to patients, their family and friends to demonstrate the unusual nature of their corneal condition.

This can be illustrated by the following two examples.

Figure 1 is an OCT scan of a keratoconic patient with acute corneal hydrops. Note the markedly oedematous (thickened) cornea with the dark spaces representing the fluid clefts (cysts) in the cornea.


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Figure 1. Keratoconic patient with acute corneal hydrops


Figure 2 is an OCT scan of a corneal graft in a 58-year-old female. The graft was 35 years old and very proud, and subsequently no longer amenable to contact lens fitting as a result of marked dehiscence at the host-donor corneal graft junction. While the patient was not convinced initially that regrafting was absolutely necessary, she was better able to understand its necessity once she visualised her unique corneal profile on the OCT scan.


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Figure 2. Very proud corneal graft


To demonstrate the value of the OCT to contact lens fitting, consider the phenomenon of lens settling, which is commonly seen with both scleral and miniscleral lenses. These lenses rest on the bulbar conjunctiva and Tenon’s capsule, both of which are very compressible tissues, and so the vault of the lens will decrease as the lens settles onto the eye and compresses these softer tissues.

In a study published a couple of years ago, John Mountford found the average lens settling following one month of lens wear to be just over 140 microns, although there was a large variation between patients.

By taking pictures of the lens at various times after insertion, the amount of lens settling even during a diagnostic fitting can be documented.

Figure 3 is an OCT scan taken 10 minutes after a miniscleral lens was inserted onto the eye of a patient with very advanced keratoconus.


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Figure 3. Miniscleral lens 10 minutes after insertion on patient with advanced keratoconus


Figure 4 is an OCT scan of the same lens taken one hour after insertion. At 10 minutes, the apical clearance at its narrowest point was about 120 microns. At one hour, the apical clearance had decreased to 40 microns as a result of lens settling.


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Figure 4. Miniscleral lens one hour after insertion, showing significant lens settling


Anterior segment OCT is invaluable for both contact lens fitting and patient education. 


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