Intacs to stabilize diurnal variation in refraction after radial keratotomy

Abstract

We present a patient who was dissatisfied with the refractive results of the radial keratotomy procedure he had 8 years previously, specifically the instability of the visual acuity and refractive error throughout the day. To reverse the biomechanical disturbance caused by the incisions, an intracorneal ring segment (Intacs, Addition Technology, Inc.) was inserted in the inferior cornea. The variation in refraction decreased from 1.50 and 2.25 diopters (D) to 0.25 and 0.50 D, resulting in a very satisfied patient.

Refractive results of cataract surgery using optical biometry and Haigis formula in eyes with refractive keratotomy

“…The method used in this study was optical biometry with the IOL Master -Zeiss ® (5.4 -5.5) which makes the calculation of axial length by partial coherence interferometry and has proved more efficient than contact ultrasonic biometry (4) . Corneal power, the focus of major controversy in the eyes with keratotomy (2) scar, is obtained by the autorefractor biometer in a central area of 2.50mm (different from manual keratometry that provides values of an area of 4.00mm (5) ). In addition to our routine corneal power provided by the biometer, we obtained an extra keratometry with topographer (Pentacam -Oculus) that in the module Holladay Report allows us to choose the keratometric value in a central area of 3.0mm (6) .…”

“…They are well informed about advances in eye surgery and demand or expect to have results that meet or exceed their expectations (1) . Another characteristic is related to the cornea that usually shows a progressive central flattening, with fluctuation of the visual acuity.When submitted to lens surgery may have a significant flattening, though temporary, which may compromise the final result (2) . Refractive (1) predictability and reproducibility of IOL calculation may be difficult due to the peculiarities of the cornea previously submitted to keratotomy.…”

Single intrastromal corneal ring segment implantation using the femtosecond laser after radial keratotomy in a keratoconic patient

“…[5][6][7] In these post-RK keratoconic patients, refractive complications cannot be treated with excimer laser refractive surgery because of corneal instability. Recently, Koppen et al 15 presented encouraging results after implantation of a single ICRS (Intacs, Addition Technology, Inc.) in a post-RK patient with diurnal variation in refraction. The tunnel for segment implantation was created manually using mechanical devices, and dehiscence of the RK corneal incisions was observed during tunnel creation.…”

On the question of progressive hyperopia correction after radial keratotomy

“…В совокупности эти изменения формы приводят к ослаблению рефракции в центральной зоне. При этом, однако, существенно нарушается природная регулярность рефракционных свойств (топографии) роговицы, которая обусловлена плавностью перехода рефракции как от одного главного меридиана к другому, так и в пределах каждого меридиана [13][14][15].…”

“…Это же обстоятельство осложняет и применение торических ИОЛ, в первую очередь из-за невозможности четкого определения положения главных меридианов. Кроме этого, при выборе данного метода коррекции необходимо учи-тывать нестабильность рефракции роговицы [27,28] и прогрессирование гиперметропии, что требует разработки и проведения специальных тестов, указывающих на возможное дальнейшее изменение «жесткости» роговицы после операции.…”