Active clinical trials for "Myopia"

To assess the long-term efficacy of the Menicon Z Night orthokeratology contact lens in controlling the progression of childhood myopia

The purpose is to assess the effect of part-time compared to full-time spectacle use in juvenile myopia control.

The study aims to examine how the vascular layer of the eyeball (choroidal layer) responds when part of the visual field is exposed to specially generated visual stimulus. The study goal will be accomplished by producing specific blur visual stimulus at a particular visual field position and measure any consistent thickness change pattern in the choroidal layer. We propose to test the hypothesis that regional changes in the choroidal thickness may be induced differently after short-term exposure to specific visual stimuli.

Corneal asphericity is expressed numerically as the "Q-value". A minus value means that corneal curvature flattens towards the periphery and the cornea is prolate in shape, but when the curvature steepens towards the periphery, the cornea is oblate in shape and has a positive Q-value. The current study evaluates the effect of LASIK eye surgery on corneal asphericity by comparing 2 software treatment platforms; the Q value customized ablation versus the conventional Wave-front optimized ablation in a fellow eye study pattern.

Participants eligible for the study will be randomized to one of three concentrations of atropine and followed for a month.

LASIK is the most commonly performed refractive surgery worldwide. It has been shown to be safe and effective procedure with predictable results over long term follow ups. With the advancement of technology, sub-Bowman keratomileusis allows thin flap of approximately 100 microns thickness thus preserving thicker stromal bed as compared to conventional LASIK. The femtosecond laser corneal flap has th advantage of producing a flap of uniform thickness, adjustable flap diameter, relatively few complications. The disadvantages of this procedure is the high cost of surgery, development of bubbles in the corneal layer and anterior chamber which may affect pupil trackingduring the procedure. Despite the emergence of femtosecond laser-assisted flap creation, mechanical microkeratomes remain the preferred choice in the majority of developing countries. Recent studies have shown that SBK corneal flap has the same advantages as femtosecond laser flap regarding flap uniformity, regularity, and accuracy with less suction time and cost, but with its specific complications as well.

This study aims to compare effects in retardation of myopia progression of combined ortho-k and 0.01% atropine therapy with those of ortho-k alone.Myopia control methods mainly focus on optical and pharmaceutical interventions . Currently, overnight-wear orthokeratology (ortho-k), is used extensively in Hong Kong with approximately 50% retardation effect. Pharmaceutical methods have focused on the use of atropine eye drops to slow myopic progression.The use of 1% atropine was limited by the manifestation of side effects and rebound effect.However, both side effect and rebound effect was minimal with 0.01% atropine.It was suggested that 0.01% was the optimum concentration for controlling myopia.The mechanisms of neither ortho-k nor atropine in myopia control are fully understood.It is believed that ortho-k and atropine act via different mechanisms.It is possible that by combining these two methods, additional retardation of myopia progression could be achieved.

Small-incision lenticule extraction (SMILE), the most recently developed refractive surgical technique, is being performed in a growing number of cases. This intrastromal keratomileusis using only a femtosecond laser is a new procedure that extracts the refractive lenticule through a small corneal incision ranging from 2 to 5 mm, with the absence of a flap and the preservation of the anterior-most stromal lamellae and Bowman's layer (except for the region of the small incision). Many studies have demonstrated that SMILE achieved comparable or superior efficacy, safety, and predictability to femtosecond laser -assisted in situ keratomileusis (FS-LASIK) and femtosecond lenticule extraction (FLEx). However, the recovery of visual acuity in the early postoperative period after SMILE is slower, compared to other refractive surgery techniques. Therefore, adjusting energy might improve postoperative visual acuity and recovery time after SMILE. Nevertheless, the optimal parameters drawn from a well-organized randomized study have yet to be elucidated. The purpose of this study was to investigate the optimal femtosecond laser energy, with the aim of improving clinical outcomes during the early postoperative period after SMILE for the correction of myopia. To this end, we used a 500 kHz VisuMax with spot-spacing control at energy levels lower than 115 nJ, based on the previous studies. Therefore, we prospectively compared visual outcomes of two groups randomly divided by different laser energies: one underwent SMILE using lower energy levels of 100, 105, and 110 nJ (L-SMILE), while the other group underwent SMILE at energy levels conventionally used of 115 to 150 nJ (C-SMILE).

The objective of this clinical trial is to evaluate the safety and effectiveness of the Carl Zeiss Meditec VisuMax™ Femtosecond Laser lenticule removal procedure for the reduction or elimination of myopia from ≥ -1.00 D to ≤ -10.00 D with ≤ -3.00 D cylinder (myopia with or without astigmatism) and MRSE ≤ -11.50 D.

This purpose of this study is to evaluate the safety and effectiveness of a topography-based custom ablation treatment using the ALLEGRETTO WAVE® Eye-Q 400 Hz laser system for treating myopia and hyperopia.