|
|
International Newsletter and Forum on Rigid Gas Permeable Contact Lenses, Corneal Shape, Health and Vision |
|
|
|
|
|
|
|
|
|
|
Cataract & Keratoconus
 Yes, keratoconus patients get cataracts, too. In a recent column in a Dutch contact lens journal, a young Dutch optometrist, Nienke Soeters, brought up a good point regarding cataracts and keratoconus. Toric intraocular lenses are becoming more commonly used - but for keratoconic eyes they may not necessarily always be a good thing. If a residual corneal cylinder is present after the procedure, a (R)GP lens will correct the corneal astigmatism - but not the internal cylinder. This may result in an unnecessarily complicated - or at least a more challenging - lens fit. In keratoconus, typically a (R)GP lens, corneal or scleral, is often needed - possibly requiring front toric optics if intraocular lenses are implanted. This topic of intraocular lenses in keratoconus was addressed recently by Nanavaty, Lake & Daya in the Journal of refractive surgery (2012) as well as a few years back by Thebpatiphat, Hammersmith & Rapuanoin (2007) in Eye & Contact Lens. Clinical & Experimental Optometry (2013) covered a case report by Lindsay, Connell & Snibson on the contact lens management of keratoconus in a patient with residual astigmatism resulting from implantation of a toric intraocular lens. Eef van der Worp |
|
Troubleshooting
Now that scleral lenses have gained so much ground in the international specialty contact lens market, there is an increasing demand for troubleshooting tips. Jeffrey Sonsino and Muriel Schornack provide one of the most detailed and thoroughly written articles on that subject in the May edition of Contact Lens Spectrum. What can we do, for instance, about wetting problems, and what about limited wearing time? Comfort and handling issues are discussed as well as lens fitting challenges. One aspect that should not be overlooked is care-related complications. Patients who experience mild conjunctival hyperemia or excessive accumulation of debris in the post-lens fluid reservoir may achieve more successful lens wear if they store their lenses in peroxide-based cleaner, the authors suggest. Perhaps even more important is the fluid with which the bowl of the lens is filled before lens application - and care products need to be based upon individual patient characteristics and their condition, they state. Also in the May edition of Contact Lens Spectrum, Patrick Caroline and Mark André, discuss an 'in-vivo' cleaning tip for scleral lenses was introduced, as was suggested by John Mountford from Australia. Photo: Greg DeNaeyer
Sonsino & Schornack, Contact Lens Spectrum - May 2013
|
|
News from Manchester
At the 2013 BCLA meeting in Manchester, a number of very interesting posters and papers were presented related to our daily (R)GP lens practice. A small selection: a study from Hong Kong by Yee, Chui and Cho looked at discontinuation after five years of orthokeratology (poster #2). Five patients were followed for over a year - but stability was reached within 6 weeks from discontinuation for all. Reeder, Hunt and Harthan presented an interesting poster (#60), analyzing 446 keratoconus patients for the incidence of corneal hydrops. Of these, 44 (9.2%) developed hydrops. They also looked at risk factors and stated that a 35-year-old African-american male or female with atopia may be more prone to developing a hydrops. The month of April, in the spring, proved to show by far the highest incidence of hydrops. A paper presented by Loetscher from New Zealand that was part of the myopia control session showed the results of a study on multifocal orthokeratology (MOK) lenses on 30 kids (ages 10-14). The results were more than promising in terms of reduction in the progression of myopia with MOK lenses. Abstracts of the posters will appear later this year in the BCLA journal Contact Lens & Anterior Eye.
|
|
Compensation of Internal Eye Aberrations
In the May edition of Optometry & Vision Science, Gifford et al. presented a study looking at corneal versus ocular aberrations after orthokeratology. Orthokeratology causes an increase in corneal surface higher-order aberrations, predominantly attributable to an increase in coma-like and spherical aberration. The profile of the induced corneal aberrations is similar to changes in ocular aberrations. However, it is known that in the normal eye, the internal eye aberrations can typically compensate for any corneal surface aberrations that are present over time. This raises the question: do orthokeratology-induced aberrations lead to an adaptation response, too? The difference in this study, found in patterns at day one versus at day seven, seems to indicate there may indeed be an ocular adaptation response toward neutralizing induced aberrations in orthokeratology lens wear.
|
|
Visual Rehabilitation
A study by Singh, Jain and Teli in Contact Lens and Anterior Eye retrospectively reviewed 158 patient records to evaluate the efficacy of contact lenses for visual rehabilitation of a series of patients with corneal scars/opacities.(R)GP lenses were fitted in 137 such eyes, and soft lenses were fitted in 25 eyes. Of all eyes in which the visual acuity was improved by two or more lines over that of the spectacle visual acuity, 85% (96 of 113 eyes) wore (R)GPs lenses. Soft lenses were attempted in 25 cases in which (R)GP lenses could not be fitted, and 17 of these were successful. All 17 patients where aphakes. Photo: Rob Koster - Oculenti.
|
A 56-year-old male patient presented with keratoglobus of his left eye, which had previously undergone a penetrating keratoplasty. He was wearing a hybrid contact lens that exhibited fluting of the soft skirt secondary to an excessively flat fit. His vision with glasses over his hybrid contact lens was limited to 20/40. The patient was refit with a full scleral lens. Successfully fitting keratoglobus requires lenses that will vault large amounts of sagittal height. Using full sclerals with diameters of 20mm or greater is generally required to achieve adequate vault. In this case, a 20mm scleral lens with a 55-diopter base curve was ultimately ordered and dispensed. The final power of -22.50D gave the patient 20/30 vision.
|
The Contact Lens Specialist Symposium 2013 will take place 28th & 29th Septemb er 2013 in The Renaissance Hotel, Bath Road, London Heathrow. Keynote speakers will be Patrick Caroline, Eef van der Worp and Randy Kojima who will take you on an exciting journey through optics - from understanding the surface of the eye to optimal contact lens fitting. Our Exhibition will guide you through lens choices as well as offer advice on how to build a successful, sustainable business. www.clss.eu
|
|
|
|
|
|
|
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-political. Its editor Eef van der Worp, optometrist, PhD, FAAO, FBCLA, FIACLE, FSLS is a lecturer for a variety of industry partners, but is not related to any specific company. Please contact us at: i-site@netherlens.com.
|
|
|
