Accelerated versus conventional corneal crosslinking for refractive instability: an update.

PURPOSE OF REVIEW: Corneal crosslinking (CXL) is a relatively new treatment modality offering refractive stability in patients with ectatic disorders. The procedure as initially described (Dresden protocol) is time consuming; accelerated protocols have been lately developed. The purpose of this review is to present the recent findings regarding the comparison of accelerated CXL with the conventional Dresden protocol. RECENT FINDINGS: A variety of accelerated protocols are described in the literature. Safety and efficacy of the procedures with regard to stability seem to be equivalent in initial studies but indirect measures of efficacy, such as demarcation line depth and laboratory measurements, do not always confirm equivalence of accelerated protocols in comparison to conventional one. Modified accelerated protocols must be developed in order to overcome this. SUMMARY: Accelerated CXL protocols seem to be a valid alternative to the conventional protocol; however, more comparative long term studies are needed to confirm the validity and to elucidate which accelerated protocol is ideal in each case.

Radiofrequency diathermy as a treatment of lipid keratopathy in a radial keratotomy incision.

Purpose: We report a case of lipid keratopathy in a radial keratotomy incision that was successfully managed with radiofrequency diathermy of the neovascular pedicle responsible for the lipid deposition. Observations: No perioperative or postoperative complications were noted. Following the procedure, the lesion showed significant decrease in lipid deposits and opacification along with disappearance of the neovascular pedicle. Conclusions and importance: Radiofrequency diathermy of neovascular pedicle may represent an effective and safe alternative treatment option for treating lipid keratopathy. This is a first ever report of lipid keratopathy inside a radial keratotomy incision that was successfully managed by radiofrequency diathermy.

Combined Astigmatic Arcuate Keratotomy with Descemet Automated Endothelial Keratoplasty.

We report the results of simultaneous astigmatic arcuate keratotomy (AK) and Descemet automated endothelial keratoplasty (DSAEK). A 55-year-old patient with a history of high myopia was referred for the management of bullous keratopathy secondary to an anterior chamber phakic intraocular lens (pIOL). IOL explantation through a 5.5-mm corneal incision, cataract extraction, and posterior chamber IOL implantation, combined with DSAEK, were performed. Postoperatively, increased astigmatism up to 2.0 diopters (Dpt) was observed, attributed to the large corneal incision, and remained stable, despite suture removal at 3 months. One year postoperatively, the graft showed signs of progressive endothelial dysfunction. A combined procedure of astigmatic AK and DSAEK was thus performed. After 6 months, topographic astigmatism was significantly reduced to 0.5 Dpt and best-corrected visual acuity increased. In conclusion, simultaneous astigmatic AK and DSAEK could be an effective combination for treating patients with well-documented pre-existing astigmatism and endothelial decompensation.

Intraocular Lens Refractive Index and Its Impact on External Surface Reflections.

PURPOSE: To determine and compare the origin of the external surface reflections produced by commonly used intraocular lenses (IOLs). METHODS: The specular reflection taking place at the anterior surface of eight types of IOLs (IOL power = 22.00 diopters [D]) with different refractive indices (RIs), optical design, and ultraviolet and blue light-filtering function were measured. The experimental set-up included a laser beam light source (3.5 mW, 532 nm) and a saline-filled model eye containing the IOL to be examined. External surface reflections were measured using a power meter, and the IOL surface reflectance (%) was compared among the eight IOLs investigated. RESULTS: External reflections from the anterior surface of the studied implants increased as the RI of the IOL material increased. The IOL models composed of high RI material (RI = 1.56 ± 0.02) were found to have a more than threefold higher external surface reflections compared to those with low RI (RI = 1.45 ± 0.02). Ultraviolet or blue light-filtering functions showed no significant correlation with the external reflectance. CONCLUSIONS: IOLs with a high RI are associated with external surface reflections that are more than threefold higher than those with lower RI. The "cat's eye" phenomenon seen in pseudophakic eyes by an outside observer strongly depends on the RI, but is independent of the filter incorporated in the IOL. [J Refract Surg. 2021;37(6):398-402.].

Burr-Assisted Peripheral Superficial Keratectomy for the Treatment of Persistent Symptomatic Peripheral Corneal Edema.

PURPOSE: To describe a simple technique of diamond burr-assisted superficial keratectomy for the treatment of peripheral corneal edema. CASES PRESENTATION: Two patients with persistent symptomatic peripheral corneal edema underwent superficial keratectomy with the use of a diamond ophthalmic burr. The efficacy of the treatment was evaluated clinically as well as with anterior segment optical coherence tomography. During the postoperative follow-up period, no adverse events were observed and corneal edema reduced significantly. The patients were asymptomatic, no epithelial cysts could be identified clinically, and visual acuity remained unchanged. CONCLUSION: Peripheral superficial keratectomy could be an effective alternative for the treatment of peripheral, symptomatic corneal edema.

Resolution of Corneal Fibrosis After Descemet's Stripping Automated Endothelial Keratoplasty: A Case Report.

PURPOSE: To report the resolution of anterior corneal fibrosis after Descemet's stripping automated endothelial keratoplasty (DSAEK), in a patient with chronic corneal edema and anterior stromal scarring. METHODS: A 63-year-old woman, with a history of Fuchs endothelial dystrophy, presented with increasing discomfort and gradual visual loss in her right eye. Clinical examination revealed long-standing bullous keratopathy accompanied by marked subepithelial fibrosis (SEF). Based on the low postoperative visual potential due to glaucomatous optic neuropathy, we decided to proceed with DSAEK. RESULTS: During the follow-up period, SEF was found to gradually resolve. Corneal clarity was restored and an improvement in visual acuity was observed up to 12 months after surgery. CONCLUSION: DSAEK alone may represent an effective therapeutic option for the restoration of impaired corneal clarity in patients with long-standing corneal edema and concomitant anterior subepithelial scarring.

A New Surgical Approach for the Management of Acute Corneal Hydrops Complicated With Corneal Perforation.

PURPOSE: To report an unusual case of a patient with keratoconus and acute hydrops complicated with corneal perforation and describe its management using a new surgical approach. METHODS: A case report and new surgical approach description. RESULTS: A 47-year-old female patient with a history of keratoconus and implantable contact lens surgery presented at our institute with symptoms of acute corneal hydrops in her right eye. On examination, best corrected visual acuity was of counting fingers in the involved eye. Slit-lamp examination revealed a small inferotemporal corneal perforation, surrounded by marked corneal edema and a positive Seidel test. Initial attempts of conservative treatment with cyanoacrylate tissue adhesive application and bandage soft contact lens placement were ineffective. We decided to proceed with an inferior, lamellar wedge resection of the diseased corneal tissue. One month postoperatively, the cornea remained clear, whereas best corrected visual acuity was 0.1. CONCLUSIONS: Lamellar wedge resection could represent an alternative surgical approach for keratoconic patients, with eccentric acute hydrops and subsequent corneal perforation that provides rapid visual rehabilitation.

Topographic changes simulating keratoconus in patients with irregular inferior epithelial thickening documented by anterior segment optical coherence tomography.

PURPOSE: To present six patients with keratoconus-like topographic changes due to inferior inhomogenous epithelial thickening, demonstrated by AS-OCT epithelium map. PATIENTS AND METHODS: We present twelve eyes of six patients evaluated in the refractive surgery consultation with Pentacam® HR Scheimpflug rotating camera system, presenting topographical irregularities suggestive of keratoconus. Slit-lamp examination, best-corrected visual acuity, Scheimpflug tomography and anterior segment optical coherence tomography epithelium map (Optovue® ) were conducted and analyzed. RESULTS: The mean age was 42 years and the female:male ratio was 2:1. Mean Kmax was 45±2 D. The mean corneal thickness at apex was 560±33 µm and the mean thickness at the thinnest location was 555±34 µm. All patients had an abnormal index of height decentration (IHD) in at least one eye. In all cases, anterior segment OCT demonstrated relative epithelial thickening over the steep area measured by tomography. The mean thickness of the inferior epithelium over the suspicious area was 60±2 µm, whereas the mean thickness of the superior epithelium was 56±2 µm. CONCLUSION: Epithelial irregularity, as measured by anterior segment OCT, should be considered as a possible contributing factor in the appearance of suspicious keratoconus-like topographies.

Peripheral hypertrophic subepithelial corneal degeneration: clinical aspects related to in vivo confocal microscopy and optical coherence tomography.

PURPOSE: To report the findings of anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM) in two patients with peripheral hypertrophic subepithelial corneal degeneration (PHSD). METHODS: Case series by restrospective chart review and imaging analysis of AS-OCT and IVCM. RESULTS: Slit lamp examination of the two patients revealed a bilateral subepithelial-elevated fibrous tissue of the superior-nasal quadrant, as well as inferior-nasal in one of the patients. Best corrected visual acuity ranged from 20/25 to 20/15. AS-OCT showed continuous, homogenous, well-demarked hyperreflective subepithelial band associated with hyperreflectivity in the anterior stroma. IVCM demonstrated normal epithelial cell morphology and arrangement and a fibrous structure subepithelial and in the anterior stroma. CONCLUSION: AS-OCT and IVCM can facilitate the diagnosis of PHSD and differentiate it from other corneal entities that present peripheral opacifications.

Combined DSAEK and intraocular lens flipping with retropupillary fixation in a patient with anterior chamber iris-claw intraocular lens and corneal edema.

An 84-year-old monocular woman was referred to our institution for the management of corneal decompensation in her only eye, the right eye. The patient had secondary implantation of an anterior chamber iris-claw intraocular lens (IOL) for IOL dislocation in the setting of pseudoexfoliation syndrome 2 years before presentation. Descemet-stripping automated endothelial keratoplasty (DSAEK) combined with retropupillary repositioning of the iris-claw IOL using a flipping technique was performed for the treatment of corneal edema. No intraoperative or postoperative complications occurred. Six months postoperatively, the corneal graft was attached and clear and the retropupillary iris-claw IOL was well positioned. The uncorrected distance visual acuity and corrected distance visual acuity improved from counting fingers preoperatively to 20/200 and 20/63, respectively, after surgery. Combined DSAEK and retropupillary refixation of a prepupillary iris-claw IOL using the flipping technique was a safe technique in this patient with corneal decompensation.

Intraoperative anterior optical coherence tomography-guided synechiolysis in a post-penetrating keratoplasty patient with peripheral corneal opacification.

PURPOSE: The aim of this study was to describe intraoperative optical coherence tomography (OCT) as an adjunctive device for peripheral synechiolysis in a post-penetrating keratoplasty patient. CASE REPORT: A 75-year-old female patient presented for follow-up 9 months after a penetrating keratoplasty in the left eye. She presented with anterior peripheral synechiae involving the graft for three clock hours. Peripheral native cornea appeared totally opaque. Synechiolysis was planned, and intraoperative OCT allowed us to detect nonclinically visible synechiae and to confirm complete synechiolysis immediately after surgery. No postoperative complication was recorded. Two months after surgery, the graft was clear and anterior segment OCT did not reveal any residual synechiae or recurrence. CONCLUSION: Intraoperative OCT is useful to overcome the difficulties in visualization through clinically opaque corneas, as it gives real-time feedback upon the anatomy, the extension of the remaining lesions, and the success of the surgery.

Characteristics of Linear Interstitial Keratitis by In Vivo Confocal Microscopy and Anterior Segment Optical Coherence Tomography.

PURPOSE: To describe the findings of in vivo confocal microscopy (IVCM) and anterior segment optical coherence tomography (AS-OCT) in a case of linear interstitial keratitis (IK), a very rare entity of unknown etiology. METHODS: IVCM and AS-OCT were used in the case of the a 23-year-old patient with recurrent unilateral linear IK. RESULTS: On AS-OCT, inflammation appeared confined to the anterior part of the stroma. Similar to color photography, inflammation appeared beaded. On IVCM, there was microcystic epithelial edema, dense fibrosis of the anterior stroma, highly reflective spiculated structures, and disorganization of the stromal architecture. CONCLUSIONS: Although linear IK appeared as localized anterior stromal inflammation on AS-OCT, panstromal inflammation was revealed by IVCM.

Melanopsin-Mediated Acute Light Responses Measured in Winter and in Summer: Seasonal Variations in Adults with and without Cataracts.

Seasonal adaptation is a ubiquitous behavior seen in many species on both global hemispheres and is conveyed by changing photoperiods. In humans this seasonal adaptation is less apparent, in part because changes in daylength are masked by the use of electrical lighting at night. On the other hand, cataracts which reduce light transmission, may compound seasonal changes related to the reduced daylength of winter. To better understand the effects of different photoperiod lengths in healthy adults without and with cataracts, we tested their melanopsin-mediated light responses in summer vs. winter. Fifty-two participants (mean age 67.4 years; 30 with bilateral cataracts and 22 age-matched controls with clear lenses; pseudophakes) were tested twice, once in summer and once in winter. At each test session we assessed the electroretinogram and pupil responses during daytime and we determined melatonin suppression, subjective sleepiness and mood in response to light exposure in the evening. Circadian rest-activity cycles and sleep from activity recordings were also analyzed for both seasons. Both groups had similar visual function. There were no seasonal differences in the electroretinogram. For the pupil responses to bright blue light, the post-illumination pupil response (PIPR) was greater in winter than summer in pseudophakes, but not in cataract participants, whereas melatonin suppression to acute light exposure showed no differences between both groups and seasons. Overall, intra-daily variability of rest-activity was worse in winter but participants felt sleepier and reported worse mood at the laboratory in evening time in the summer. Those with cataracts had poorer sleep quality with lower sleep efficiency, and higher activity during sleep in winter than summer. In this study, the PIPR showed a seasonal variation in which a larger response was found during winter. This variation was only detected in participants with a clear intraocular lens. In the cataract group, visual function was not impaired yet these participants showed a lack of seasonal changes in the pupil response to blue light and poorer sleep in winter. These findings raise the question for tailored lighting conditions for cataract patients in order to counter potentially deleterious effects of living with chronically lower light exposure.

Tolerance and Relative Utility: Two Proposed Indices for Comparing Change in Clinical Measurement Noise Between Different Populations (Repeatability) or Measurement Methods (Agreement).

Reaching a consensus in terms of interchangeability and utility (i.e., disease detection/monitoring) of a medical device is the eventual aim of repeatability and agreement studies. The aim of the tolerance and relative utility indices described in this report is to provide a methodology to compare change in clinical measurement noise between different populations (repeatability) or measurement methods (agreement), so as to highlight problematic areas. No longitudinal data are required to calculate these indices. Both indices establish a metric of least to most effected across all parameters to facilitate comparison. If validated, these indices may prove useful tools when combining reports and forming the consensus required in the validation process for software updates and new medical devices.