SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Keratoconus

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Combination of riboflavin/UVA cross-linking (CXL) and excimer laser ablation is a promising therapy for treating corneal ectasia. The cornea is strengthened by cross-linking, while the irregular astigmatism is reduced by laser ablation. This study aims to compare the efficacy of excimer laser ablation on porcine corneas with and without cross-linking.

Concepts: Laser, Cornea, Corneal transplantation, Refractive surgery, Contact lens, LASIK, Excimer laser, Keratoconus

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: To assess the relationship between the thinnest corneal location and the steepest and maximum elevation corneal locations in subjects with keratoconus and the effect of gas permeable contact lens wear on the location of these points.

Concepts: Cornea, Lens, Orthokeratology, Contact lens, Contact lenses, Keratitis, Keratoconus, Scleral lens

28

To determine criteria for keratoconus or postoperative LASIK ectasia progression or improvement based on Pentacam HR (Oculus Optikgeräte GmbH) measured steepest corneal curvature.

Concepts: Cornea, Refractive surgery, Keratoconus

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PURPOSE: To evaluate the refractive and corneal topographical changes of overnight orthokeratology in myopia with two brands of contact lenses. METHODS: Fourty-four eyes of 22 myopic patients with manifest refraction spherical equivalent (MRSE) of -1.00 to -5.00 D (cylinder≤-1.0) were fitted with either DreamLens (Hanita Lenses Investments, Hanita, Israel) (group A) or Rinehart-Reeves (R&R; Danker Laboratories, Sarasota, FL) (group B) reverse-geometry lenses. Each subject eye was evaluated in regards to the uncorrected and corrected distance visual acuities, manifest refraction, slit lamp biomicroscopy, and corneal topography at each follow-up examination. RESULTS: The follow-up was 1 year. For groups A and B, the mean uncorrected distance visual acuity was -0.02±0.10 logMAR (20/20) and -0.08±0.12 logMAR (20/20) respectively at year-1 examination. The mean MRSE decreased from -2.70±0.9D to -0.50±0.08D in group A and -3.1±1.1 to -0.62±0.18D in group B at week-1; and remained stable thereafter in each group. For both groups, starting with week-1, the mean anterior best-fit sphere (ABFS) was statistically significantly flatter from baseline. A high correlation was found between the change in apical corneal power (ACP) and MRSE (r(1)=0.79, r(2)=0.71), and there was a good correlation between the change in ABFS and MRSE (r(1)=0.67, r(2)=0.64) in both groups. No significant ocular adverse events were observed during study. CONCLUSIONS: Both types of contact lenses safely and effectively decreased the myopic refractive error at 1 year follow-up. The refractive effect was mainly induced by the changes in the anterior corneal shape and the ACP.

Concepts: Visual acuity, Cornea, Myopia, Lens, Orthokeratology, Contact lens, Refractive error, Keratoconus

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PURPOSE: To explore the use of the Pulsar Z1 solid-state 213 nm photorefractive laser platform in topography-guided transepithelial photorefractive keratectomy (PRK) for irregular astigmatism. SETTING: Moorfields Eye Hospital, London, United Kingdom. DESIGN: Prospective clinical case series. METHODS: Patients with irregular astigmatism after previous refractive surgery or corneal transplantation were treated with topography-guided transepithelial PRK. Preoperatively and 1-year postoperatively, corrected distance visual acuity (CDVA) and secondary outcome measures (including manifest refraction, contrast sensitivity, haze score, index of surface variation, root-mean-square higher-order aberrations, and subjective visual change) were compared between groups. Adjunctive mitomycin-C was not used. RESULTS: Seven patients had previous refractive surgery, and 7 had previous corneal transplantation. All but 2 patients with a marked haze response had subjective gains in vision and improved CDVA. Gains in CDVA for patients with irregular astigmatism after previous refractive surgery (median 2 lines gain; range 0 to 2 lines gained) were higher than for patients with irregular astigmatism after keratoplasty (median 0 lines; range 5 lines lost to 4 lines gained). Trends in secondary outcome measures were similar, with greater variation in post-keratoplasty patients. Haze scores were higher in post-keratoplasty patients. CONCLUSIONS: 213 nm topography-guided transepithelial PRK was easy to perform and well tolerated by patients with irregular astigmatism. Most patients gained CDVA; however, increased haze responses were observed in post-keratoplasty cases. FINANCIAL DISCLOSURE: Neither author has a financial or proprietary interest in any material or method mentioned.

Concepts: Surgery, Laser, Visual acuity, Cornea, Ophthalmology, LASIK, Keratoconus, Photorefractive keratectomy

27

Mini-scleral lenses are an increasingly popular contact lens modality; however, there are relatively few reports regarding the unique aspects of their fitting and potential complications. We report a complication of mini-scleral lens wear in a 44-year-old female patient using the lenses for keratoconus. Her mini-scleral contact lenses were non-fenestrated and fitted to vault over the cornea and seal at the periphery. The patient presented with an acute red eye (non-ulcerative keratitis), characterised by unilateral severe conjunctival and limbal hyperaemia, corneal infiltration and pain. Refitting the lens to increase the corneal vault clearance did not prevent recurrence of the keratitis, some five months later. Successful prevention of further episodes of the acute red eye was achieved through improved patient compliance with lens cleaning, disinfection and lens case procedures. Lens hygiene may be particularly important for mini-scleral lenses with a sealed fitting.

Concepts: Eye, Cornea, Lens, Orthokeratology, Contact lens, Contact lenses, Keratitis, Keratoconus

26

Scleral contact lenses (ScCL) have gained renewed interest during the last decade. Originally, they were primarily used for severely compromised eyes. Corneal ectasia and exposure conditions were the primary indications. However, the indication range of ScCL in contact lens practices seems to be expanding, and it now increasingly includes less severe and even non-compromised eyes, too. All lenses that partly or entirely rest on the sclera are included under the name ScCL in this paper; although the Scleral Lens Education Society recommends further classification. When a lens partly rests on the cornea (centrally or peripherally) and partly on the sclera, it is called a corneo-scleral lens. A lens that rests entirely on the sclera is classified as a scleral lens (up to 25mm in diameter maximum). When there is full bearing on the sclera, further distinctions of the scleral lens group include mini-scleral and large-scleral lenses. This manuscript presents a review of the current applications of different ScCL (all types), their fitting methods, and their clinical outcomes including potential adverse events. Adverse events with these lenses are rare, but the clinician needs to be aware of them to avoid further damage in eyes that often are already compromised. The use of scleral lenses for non-pathological eyes is discussed in this paper.

Concepts: Eye, Cornea, Lens, Orthokeratology, Contact lens, Contact lenses, Keratoconus, Scleral lens

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To evaluate the safety and efficacy of corneal collagen crosslinking (CXL) for the treatment of corneal ectasia after laser refractive surgery.

Concepts: Surgery, Laser, Cornea, Refractive surgery, Astigmatism, LASIK, Keratoconus, Multicenter trial

17

To assess patient satisfaction and perceived outcomes with different methods of refractive error correction through annual surveys administered over a 3-year period.

Concepts: Myopia, Keratoconus

7

Laser in-situ keratomileusis (LASIK) is a commonly performed surgical procedure used to correct refractive error. LASIK surgery involves cutting a corneal flap and ablating the stroma underneath, with known damage to corneal nerves. Despite this, the epidemiology of persistent pain and other long-term outcomes after LASIK surgery are not well understood. Available data suggest that approximately 20-55% of patients report persistent eye symptoms (generally regarded as at least 6 months post-operation) after LASIK surgery. While it was initially believed that these symptoms were caused by ocular surface dryness, and referred to as “dry eye,” it is now increasingly understood that corneal nerve damage produced by LASIK surgery resembles the pathologic neuroplasticity associated with other forms of persistent post-operative pain. In susceptible patients, these neuropathological changes, including peripheral sensitization, central sensitization, and altered descending modulation, may underlie certain persistent dry eye symptoms after LASIK surgery. This review will focus on the known epidemiology of symptoms after LASIK and discuss mechanisms of persistent post-op pain due to nerve injury that may be relevant to these patients. Potential preventative and treatment options based on approaches used for other forms of persistent post-op pain and their application to LASIK patients are also discussed. Finally, the concept of genetic susceptibility to post-LASIK ocular surface pain is presented.

Concepts: Surgery, Laser, Cornea, Ophthalmology, Refractive surgery, LASIK, Keratoconus, Keratomileusis