I-site March 2010

International Newsletter and Forum on Rigid Gas Permeable Contact Lenses, Corneal Shape, Health and Vision

March 2010

In This Issue

Column

Myopia Development

Scleral Lenses

I(n)site-the-practice

(R)GP art

Agenda

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Column

Surgery (or not)

One of the most frequent questions that practitioners have regarding keratoconus is: When do I refer for a keratoplasty? A recent study in Australia looked at unilateral keratoplasties and found, as have many studies in the past, that suboptimal visual outcome is often the reality after the procedure. A recent study evaluated the use of LASIK and PRK after keratoplasty to improve post-keratoplasty vision. Lamellar keratoplasty appears to have advantages over the penetrating version, although controversy exists. But either way the outcome it seldom is perfect in terms of visual outcome. The truth is: many post-keratoplasty patients still end up with (R)GP contact lenses after the procedure, which is often a huge disappointment to them (and it is our task to prepare them for that). Smiddy et al back in 1988 published a study with the title: Keratoconus: contact lens or keratoplasty? They found that contact lenses could have been fitted in 69% of eyes that were referred for keratoplasty. In my opinion, it is best to keep these patients in contact lenses for as long as possible. Especially with today's lens designs, we have many options to keep patients very satisfied for a long time.

Eef van der Worp

Myopia

Myopia Regulation: Myth or Megatrend?

One of the most exciting new developments in our field remains the potential to slow down myopia progression, at least to some degree, in young children. A nice article in Review of Optometry by Jerome Legerton and Brian Chou looks at the possible trend (or myth) of this promise. Meanwhile, a paper published in the January 2010 edition of Optometry and Vision Science (full access PDF) indicates that, while previous investigators have suggested that peripheral hyperopic defocus may play a role in the development and progression of myopia, they found that single-vision spectacle lenses used to correct myopia can result in increased hyperopic defocus at the peripheral retina in the eyes of Chinese children. The magnitude of this increase tends to escalate with increasing refractive error and eccentricity, especially in cases with moderate levels of myopia. But lightning conditions may also play a protective role in myopia development. Other pieces of the puzzle?

Scleral Lenses

Sclerallens.org

The Scleral Lens Education Society (SLS) is a non-profit organization committed to teaching contact lens practitioners the science and art of fitting all designs of scleral contact lenses for the purpose of managing corneal irregularity and ocular surface disease. SLS supports public education that highlights the benefits and availability of scleral contact lenses. Go to www.sclerallens.org to register (free) to access more information about scleral lens fitting, with case reports and forums as well as for information on how to become a fellow of the society.

I(n)-site-the-practice

A good impression

Scleral lens fitting is a 'different ball game' compared to fitting corneal lenses. Oftentimes scleral lenses will settle into the scleral conjunctiva and leave an impression ring that will be noticeable after removal. This is of no consequence as long as there is no blanching of the vessels. Significant blanching and limbal congestion indicates seal-off, which will make the lens unwearable. For more on this topic see

this month's I(n)-site-the-practice by Greg DeNaeyer. This article is an excerpt from the sclerallens.org website's forum (see item above). Everybody is invited to join in.

(R)GP-ART

Psychedelic Height

Sagittal height of the anterior ocular surface is playing an increasingly important role in the contact lens industry. Placido disc corneal topographers are becoming more accurate at calculating sagittal height from corneal curves, which has many clinical applications. Scheimpflug instruments and optical coherence tomography can image ocular height directly, and over a much larger area. This psychedelic image shows the entire anterior ocular surface, including the eyelids, taken with an interferometer. The fringes represent moiré patterns, from which ocular height can be processed. Photo: Frans Jongsma and John de Brabander (Maastricht, the Netherlands).

International Agenda

Upcoming Meetings

I-site is an educational newsletter that is distributed on a monthly basis and provides an update on rigid gas permeable related topics (scientific research, case reports and other publications worldwide). I-site is objective and non-politcal. Its editor Eef van der Worp, optometrist, PhD, FAAO, FBCLA, FIACLE is a lecturer for a varity of industry partners, but is not related to any specific company. Please contact us at: i-site@netherlens.com.