麻豆传媒

CHICAGO -- Two treatments in development, one surgical and the other noninvasive, show early promise in improving presbyopia, researchers reported here.

Preliminary findings with the use of an allogenic refractive lenticule and electrostimulation of the ciliary muscle were presented at the 2016 American Academy of Ophthalmology meeting.

A femtosecond laser-created allogenic inlay obtained from a small incision lenticule extraction (SMILE), referred to as PEARL (presbyopic allogenic refractive lenticule), allowed six emmetropic presbyopic patients to be independent of glasses for near, intermediate, and distance for routine visual tasks, reported Soosan Jacob, MS, from Dr. Agarwal's Refractive and Cornea Foundation, Chennai, India.

Synthetic inlays used for presbyopia correction can promote an inflammatory response and potentially interfere with diffusion of oxygen and nutrients into the anterior stroma. The allogenic SMILE inlay, by contrast, is biocompatible, thereby avoiding these problems, ensures stable corneal conditions and has already been used successfully for the treatment of other ocular diseases such as hypermetropia, aphakia, and keratoconus.

As with synthetic corneal inlays, "it has the advantage of reversibility and adjustability," said Jacob.

The procedure creates an area of prolateness over the pupil in the presbyopic eye with the intent to increase the depth of field. The nondominant eye of six patients with presbyopia were treated with PEARL.

Anterior segment optical coherence tomography "showed exactly what we wanted; it showed an area of hyperprolateness in the central 3 mm zone, and this increased radius of curvature in the central cornea was responsible for giving the increased near vision," she said.

All six operated eyes improved acuity by three to five lines. Uncorrected near visual acuity at 33 cm was J3 in one eye, J2 in three eyes and J1 in two eyes. Uncorrected intermediate visual acuity at 67 cm ranged from J3 to J5, and uncorrected distance acuity remained 20/20 in both the operated eye and binocularly. Over follow-up of 4 to 6 months, there was no regression in near visual acuity and uncorrected distance acuity was maintained. Reading speed was also faster in the operated versus non-operated eye.

There were no inlay-induced complications and no patient complained of night glare or halos.

Electrically stimulating the ciliary muscle was able to restore accommodation in a series of patients with early presbyopia, resulting in an improvement in near acuity, said Luca Gualdi, MD, form Diagnostica Oculistica e Microchirurgia Ambulatoriale, Rome, Italy.

The concept of electrostimulation is one in which rhythmic, low voltage and constant contraction produced by an electrostimulator provides passive exercise to the ciliary body to increase its dimension, contraction strength, and efficiency.

The electrostimulator device is comprised of a generator, cable and a polycarbonate contact lens attached to four 3-mm electrodes. Four cables are connected from the core of the contact lens directly to the electrostimulator. The internal side of the contact lens is in contact with the bulbar conjunctiva. Treatment duration is 8 minutes and consists of a series of 2-second contractions followed by 6 seconds of rest. The treatment can be performed monolaterally or bilaterally.

Forty-six patients (mean age 48.1 years) with emmetropia or low hyperopia and early presbyopia (< +1.5 D) underwent bilateral electrostimulation and were included in the study.

By the second treatment session, a significant (P<0.05) improvement in uncorrected near vision (40 cm) of 0.10 logMAR was observed, with a corresponding improvement in intermediate vision (70 cm) of 0.12 logMAR. Reading speed time decreased from 219.5 seconds at baseline to 209.3 seconds after the first treatment, and improved further to 190.9 seconds after the second treatment (P<0.05 vs baseline). Contrast sensitivity increased by one line following the second treatment compared with baseline (P<0.05).

Significant improvements in near visual acuity and reading time, however, were restricted to patients younger than 50 years, said Gualdi.

The amount of accommodation as measured by the Duane Test decreased from 43 cm pretreatment to 37 cm post treatment. Ultrasound biomicroscopy taken under accommodation showed a 0.10-mm increase in lens thickness, a 0.16-mm decrease in the anterior ray of curvature of the lens and a 0.08-mm decrease in the posterior ray of curvature from pretreatment to post-treatment, "resulting in improved accommodation response after the microelectrostimulation of the ciliary muscle treatment," he said.

Based on these preliminary results, the optimal "attack dose" appears to be four treatments within the first 2 months followed by one maintenance treatment every 3 months, he said.