GSLS SCIENTIFIC POSTERS

GSLS Posters: A First Look

Scientific poster highlights from the 2016 Global Specialty Lens Symposium.

By Edward S. Bennett, OD, MSEd, FAAO, & Carl Kramer, OD

The 10th annual Global Specialty Lens Symposium (GSLS), a comprehensive clinical program limited to specialty contact lenses, was held Jan. 21 through 24, 2016 in Las Vegas. This year’s meeting was attended by a record 600+ eyecare professionals.

In addition to many hours of invaluable education, GSLS also provides the opportunity for the submission of posters in both scientific and clinical categories. This year, more than 100 posters were prominently displayed at the meeting. Here, we present the highlights from some of the most interesting research that resulted from these posters.

1. Scleral Lens Tolerance After Cornea Crosslinking (Visser ES, Soeters N, Tahzig NG, 2016)

The purpose of this study was to evaluate subjective and objective evaluation of scleral lens tolerance and fitting before and after cornea collagen cross-linking (CXL) for progressive keratoconus.

Unilateral evaluations were made of 18 subjects who were scleral lens wearers prior to CXL and resumed lens wear after the procedure. Subjective and objective vision data were collected prior to, and one year after, CXL. A standard CXL system (i.e., UV-X system, 370nm, and 3mW/cm²) was used, and the scleral lenses were nonrotationally symmetrical and manufactured from high-oxygen-permeable materials.

For the most part, the results were very encouraging. Subjective scleral lens visual quality showed a slight increase, and the spectacle-corrected distance visual acuity without scleral lens wear demonstrated significant improvement from baseline. The scleral lens fitting and surface quality were graded as optimal or acceptable in all 18 eyes that were evaluated. Additionally, scleral lens tolerance remained stable after CXL.

The importance of reevaluating the scleral lens fitting after CXL was emphasized, as a large number of lens power and design changes occurred after CXL, including 11 lenses needing a spherical power change, nine requiring a change in scleral radius, seven requiring a change in sagittal depth, six necessitating a change due to scleral toricity, and five requiring a cylinder power addition.

2. SCOPE Study: Indications for Scleral Lens Wear (Nau A, Nau C, Shorter E, Harthan J, Barr J, Schornack M, 2016)

The purpose of this study was to report on the current indications for scleral lens fitting by self-identified scleral lens fitters by international survey. This 19-question survey was administered via email, and responses were analyzed by the Mayo Clinic Survey Research Center. A total of 4,633 eyecare providers were contacted with 989 responses received, which represented almost 85,000 patients. The responses of individuals who had fit, at minimum, five scleral lenses were analyzed in detail.

After analysis of the data, 74.2% of the respondents stated that they used scleral lenses for cases of corneal ectasia. Of that 74.2%, 97.3% of the responses were for management of keratoconus, with the remaining 2.7% being pellucid marginal degeneration, post-corneal transplant, post-refractive surgery, and post-trauma. The other 25.8% of the respondents were divided as follows: 16.1% of the respondents indicated that they used scleral lenses for ocular surface disease, and 9.7% indicated that they used scleral lenses for correction of refractive error.

From this analysis of the survey data, it is clear that the primary indication for use of scleral lenses for many practitioners is keratoconus. However, it is important to note that ocular surface disease seems to be an emerging reason for prescribing scleral lenses for patients.

3. SCOPE Study: Demographics of Scleral Lens Fitters (Nau C, Harthan J, Shorter E, Barr J, Nau A, Schornack M, 2016)

This was a separate component of the aforementioned study, in which a subset of the 19 questions that were asked pertaining to scleral-fitting practitioner demographics were analyzed. Specifically, the questions pertained to topics such as age of fitters, when they initiated fitting lenses, form of practice, and how many lenses they fit. The number of respondents for each question ranged from 623 to 806.

When asked how many scleral lenses they had fit in their career, 65% indicated that they had fit 50 or fewer; 13% reported fitting 200 or more. Sixty-nine percent of lens fitters reported fitting an average of one to five lenses per month over the last year; incredibly, two fitters (0.3%) reported fitting between 100 to 150 patients per month with scleral lenses.

The age of reported scleral lens fitters was quite similar for the decades from age 25 to age 65. It also was found that the majority of lens fitters are either in partnership/group practice or in an individual private practice. In addition, it was found that the majority of lens fitters who responded to the survey have been fitting scleral lenses since at least 2010.

4. Pupil Diameter and Variable Multifocal Zone Sizes Relate to Success (Lampa M, Davis R, Becherer PD, McCorkle L, Hayes J, 2016)

The purpose of this study was to examine the effect of pupil size in relation to near-center and peripheral optic zone diameters as a predictor of positive patient outcomes when finalizing a custom soft multifocal contact lens prescription. Data were analyzed from 48 successful and 39 unsuccessful custom soft multifocal lens patients, with a total of 91 eyes in the successful group and 70 eyes in the unsuccessful group. Near-center and peripheral zone diameter of the SpecialEyes 54 multifocal contact lenses were prescribed based on a pupil size methodology, in which the sizes of the different optical zones were prescribed based on patient pupil size.

Results of this study indicated that prescribing optical zone sizes based on pupil diameter had a clinically and statistically relevant effect on patient success with both the center-near and peripheral zone sizes.

While the analysis of their data showed that pupil size was a statistically significant factor to consider when prescribing optic zone size, the study did not reveal why some patients were successful with these lenses and others were not. Further analysis of the data showed that pupil size and radius were the best predictors of success with the lenses in this study. The regression models devised in this study showed that the peripheral zone diameter of the lenses was the strongest predictor of success. They also showed that patients fit with lenses not using the pupil size-dependent fitting methodology were more likely to fail.

5. Comparing Corneal Shape Measurements of Four Topographers (Spors F, Tsang D, Hsieh E, Ardakani D, Barbosa YM, Egan DJ, Shen J, McNaughton LE, 2016)

Corneal topography instruments typically provide information on corneal shape that is valuable for contact lens fitting. This includes apical radius, sim K, and e-value, with sim K being more meaningful compared to apical radius when fitting contact lenses.

The purpose of this study was to compare four topographers in terms of possible statistically significant and clinically meaningful differences in sim K and e-value measurements. The specific instruments being compared included the Medmont E300 (Medmont International PTY Ltd), Oculus Keratograph 4 (Oculus Inc.), Zeiss Atlas 9000 (Carl Zeiss Meditec, Inc.), and the Topcon KR-8000PA (Topcon Medical Systems, Inc.).

The authors found that three of the topographers produced clinically comparable results (Medmont E300, Oculus Keratograph 4, and Zeiss Atlas 9000) when measuring sim K and e-values for healthy corneas. Therefore, they proposed that these instruments can be used interchangeably when obtaining information from healthy human corneas.

They found, in particular, that a clinically relevant difference existed for e-values, which the Topcon KR-8000PA topographer generally underestimated as compared to the other topographers.

And More ...

These posters represented only a very small amount of the research being presented at the 2016 GSLS. More findings from what has become the largest contact lens symposium in North America will be presented in the March and April issues of Contact Lens Spectrum, with a feature in April highlighting the information presented at major sessions of this meeting. CLS

For references, please visit www.clspectrum.com/references and click on document #243.

	Dr. Bennett is assistant dean for Student Services and Alumni Relations at the University of Missouri-St. Louis College of Optometry and is executive director of the GP Lens Institute. He is also clinical features editor for Contact Lens Spectrum. You can reach him at ebennett@umsl.edu.
	Dr. Kramer is the current cornea and contact lens resident at the University of Missouri-St. Louis College of Optometry.