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SKILL Biometry
Published in Sam Evans, Patrick Watts, Ophthalmic DOPS and OSATS, 2014
A number of keratometric (K) measurements are made, and, once again, the surgeon should ensure consistency in the readings. Inconsistent results suggest inaccuracy and should not be relied on. In this situation, either repeat the assessment, undertake separate corneal topography or disregard the corneal cylinder and aim for astigmatically neutral surgery. If efforts are made to correct the corneal cylinder during cataract surgery (on axis incisions, opposite clear corneal incisions or limbal-relaxing incisions) then the steep meridian must be identified and the chosen astigmatic corrective techniques employed with this in mind.
Can toric IOL rotation be minimized? Toric IOL-Capsular Tension Ring suturing technique and its clinical outcomes
Published in Seminars in Ophthalmology, 2022
Today, cataract surgery is also considered as a refractive surgery. Patients want to achieve good visual acuity without the need for spectacles or contact lenses. However, a majority of the patients undergoing cataract surgery have a visually significant amount of anterior corneal astigmatism. In a study where biometry data sets of 23,239 eyes were examined, 63.96% of the eyes had <1 D of anterior corneal astigmatism and 36.05% had ≥1 D of anterior corneal astigmatism.1 Various methods, including limbal relaxing incisions, opposite clear corneal incisions, laser arcuate incisions, Excimer laser, and toric IOL implantation, have been performed as treatments for astigmatism in these patients.2–4 Out of these, toric intraocular lens (IOL) implantation has shown highly satisfactory results in the treatment of astigmatism in cataract patients.5
Femtosecond Laser Assisted Cataract Surgery: A Review
Published in Seminars in Ophthalmology, 2021
Multiple nomograms exist for calculation of astigmatic correction by manual limbal relaxing incisions (LRIs) including Donnenfeld, Lindstrom, and Nichaman Age & Pachymetry Adjusted. There are limited published nomograms for FSL created AIs such as those created by Wortz & Gupta and Baharozian et al. Wortz & Gupta’s nomogram aims to correct low levels of astigmatism ranging from 0.25 D to 0.99 D and makes some key assumptions: surgically induced astigmatism incorporated in the formula was based on a single surgeon’s outcome, the temporal clear corneal main incision is less than 2.75 mm and always placed at 180 degrees in right eyes and 0 degrees in left eyes, and anterior keratometry values are used.43 Patients undergoing FLACS with anterior penetrating AIs using this nomogram were more likely to achieve 20/20 vision postoperatively compared to MP without astigmatism correction.43 Baharozian et al.’s FSL anterior penetrating AI nomogram is a modification of Donnenfeld’s manual LRI nomogram by accounting for the influence of posterior corneal astigmatism relative to the type of astigmatism being treated, uses a 9.0 mm optical zone, and is optimized for patients with <1.25 D of astigmatism. More than half the patients had residual refractive astigmatism <0.5 D when utilizing this nomogram.44
3D Printable, Modified Trephine Designs for Consistent Anterior Lamellar Keratectomy Wounds in Rabbits
Published in Current Eye Research, 2021
Fang Chen, David Buickians, Peter Le, Xin Xia, Spencer Q. Montague-Alamin, Ignacio Blanco Blanco Varela, David C. Mundy, Caitlin M. Logan, David Myung
The guarded trephine concept has translational potential in a number of ways. First, it is a low-cost, simple, and reproducible way for pre-clinical researchers to perform partial-thickness keratectomies on animal eyes. This is important because there are currently no vacuum trephines available designed specifically for animal corneas, which are smaller than human corneas. Moreover, OCTs and lasers dedicated to animal use are not always available to researchers due to their cost. To fill this need for ways to reproducibly create corneal stromal wounds in animal eyes, we have described here a “do-it-yourself” (DIY) stopper element that can be added to an existing trephine or biopsy punch at a specific distance between the trephine blade edge and a stopper can help create a cut with the desired depth. Future iterations of this can include an outer stopper as well which may further improve consistency. The device concept discussed here is analogous to guarded blades used for deep, sub-total corneal incisions such as those used for astigmatic keratotomies and limbal relaxing incisions. With the emergence of extracellular matrix therapies and lamellar biosynthetic grafts as promising new ways of addressing corneal blindness, simple, low-cost ways of excising corneal stroma could also be useful in under-resourced settings for human patients as well.