Phase IIIa outcomes very promising for hydrogel corneal inlay

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Implantation of a hydrogel corneal inlay into the non-dominant eye is being investigated in a phase IIIa FDA trial for presbyopia correction in emmetropic patients.

See how Jeffrey Whitman, MD, of Dallas, places the new vision inlay in the eye of an emmetropic patient. (Video courtesy of ReVision Optics and Jeffrey Whitman, MD)

San Francisco-An aspheric hydrogel corneal inlay (Raindrop Near Vision Inlay, ReVision Optics) appears very promising for presbyopia correction in emmetropic patients.

Preliminary results from all patients who have reached 6 months of follow-up in a phase IIIa FDA trial show that implantation of the device in the non-dominant eye is a safe and effective treatment, said Stephen G. Slade, MD, at the annual meeting of the American Society of Cataract and Refractive Surgery.

Dr. Slade

The transparent inlay, which measures 2 mm in diameter, is 32 µm thick, and is placed onto the stroma beneath a 150-µm femtosecond laser-created flap, improves near and intermediate vision by steepening the central cornea.

Dr. Slade, private practice, Houston, was an investigator in an earlier study, and he presented data from the first 75 eyes enrolled in the multicenter pivotal study. Eligible patients had MRSE ranging from –0.50 to +1 D, distance uncorrected visual acuity (UCVA) of 20/25 or better bilaterally, and near UCVA worse than 20/40 in the non-dominant eye.

Mean UCVA values for the eyes with the implant at baseline were ~20/20 at distance (4 m), ~20/45 at intermediate (80 cm), and ~J7 at near (40 cm). At the 6-month visit, mean UCVA improved by 5.4 lines to J1+ at near and by 2.8 lines to 20/25 at intermediate. While there was an average 1-line loss in mean distance UCVA in eyes with the implant to ~20/25, results of a quality of vision survey showed difficulty with tasks involving distance vision was not affected at all.

Visual symptom questionnaire responses showed no reports of severe glare, halos, blurred vision, double vision, or fluctuation in vision. Moderate glare and moderate halos were reported at rates of 3% and 5%, respectively. There were no cases of interface haze or any other safety issues in the cohort.

The transparent inlay, shown above in comparison with the head of a penny, measures 2 mm in diameter and 32 µm in thickness. (Photo courtesy of ReVision Optics)

An unmet need

“Correction of presbyopia is the biggest unmet need in ophthalmology for the adult population,” Dr. Slade said. “Therefore, we are very excited about these results that so far are meeting FDA benchmarks for approval indicating that the hydrogel corneal inlay is a very promising solution for treating presbyopia.”

Contrasting the results with monovision as a standard for presbyopia correction, Dr. Slade noted that whereas there is an equal trade-off in monovision in terms of the magnitude of loss in distance vision versus the gain in near, patients undergoing the inlay procedure benefit with a much greater gain in near vision relative to a minor loss at distance.

“With monovision, there is essentially a 1:1 exchange between the increase in near vision and the loss at distance,” he said. “For the inlay procedure, however, the results from this patient series show the ratio of gain in near vision to loss in distance vision exceeds 5:1.”

The inlay has efficacy and safety advantages relative to other treatments for presbyopia based on considerations of centration ease and removability, he noted.

“A multifocal contact lens is very safe because it is easily removed, but it has limitations for predictably improving near vision because it does not center well, and it is tolerated poorly by many patients,” Dr. Slade said. “Presbyopia-correcting IOLs are also fairly safe, but removal requires intraocular surgery and their centration is not predictable because it depends on the response of the capsular bag.

“Presbyopia-correcting LASIK procedures are well-centered, but are not that easily reversible,” he added. “Only the inlay is both easily centered and easily removed.”

Effect similar to natural accommodation

While skeptics have questioned how the inlay can improve near vision to such a great extent by inducing a power change over such a small central diameter, results of a study by Adrian Glasser, PhD, show that the optical effect of the inlay is similar to that occurring with natural accommodation (J Vis. 2004;4:299-309). Dr. Glasser and colleagues used a primate model and a Shack-Hartmann wavefront sensor to investigate changes in ocular aberrations occurring over the lens equatorial diameter during accommodation.

The results showed a pronounced and relatively uniform change in optical power centrally, over a 3-mm diameter, with a rapid decrease beyond that area out to the lens periphery, Dr. Slade explained.

Stephen G. Slade, MD

E: sgs@visiontexas.com

Dr. Slade is a member of the Board of Directors for ReVision Optics.

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