Armand Borovik

Enhancing Descemet Membrane Endothelial Keratoplasty in Postvitrectomy Eyes With the Use of Pars Plana Infusion

Purpose: To present a modified surgical technique to perform Descemet membrane endothelial keratoplasty (DMEK) in previously vitrectomized eyes and to analyze its safety and efficacy. Methods: A retrospective analysis of previously vitrectomized eyes that underwent DMEK at Toronto Western Hospital was performed. The modified DMEK technique that was used included placement of a posterior pars plana infusion to reduce fluctuations in the anterior chamber depth and its excessive deepening. Results: Twelve eyes of 12 patients (5 females and 7 males) aged 65.3 ± 21.5 years were included. Mean best-corrected visual acuity improved significantly from 1.72 ± 0.62 logMAR (mean Snellen ∼20/1040) preoperatively to 1.01 ± 0.64 logMAR (mean Snellen ∼20/200) at 6 months postoperatively (P = 0.017). Mean donor endothelial cell density was 2658 ± 229 cells/mm2 preoperatively and 1732 ± 454 cells/mm2 at 6 months after the procedure (mean percentage cell loss of 31.8%) (P = 0.046). There were no significant intraoperative complications, and no graft failures. One eye had graft detachment, which resolved after 2 rebubbling procedures. One eye had retinal detachment, which was corrected surgically. Conclusions: The use of posterior pars plana infusion in previously vitrectomized eyes stabilizes the anterior segment during DMEK, allowing for performance of DMEK surgery, and can potentially reduce intraoperative and postoperative complications.

Randomized, masked, in vitro comparison of three commercially available tear film osmometers

Purpose The purpose of this study was to compare the precision and accuracy of commercially available tear film osmometers. Methods Contrived tear solution target values representing the physiological range of tear osmolarity (normal eyes 297 mOsm/L, moderately dry eyes 342 mOsm/L, and severe dry eyes 383 mOsm/L) were constructed using a mix of mono- and divalent electrolytes, metabolites, serum albumin, and pH balanced to 7.4. Solution values were randomized and masked from the investigators during testing. Osmometers (Wescor 5520 Vapro Pressure Osmometer: device A, TearLab Osmolarity System: device B, and i-Med Pharma i-Pen: device C) were calibrated according to manufacturer instructions. Each level was tested 64× on each osmometer across two sites. Accuracy was reported as a correlation coefficient against expected linear dilutions, precision was calculated as percent coefficient of variation. Results Device A reported a correlation with known solutions of r2=0.98, with averages of 305.6±4.0, 352.2±5.5, and 389.8±4.0 mOsm/L, and coefficient of variations (CVs) of 1.3%, 1.6%, and 1.0%, respectively. Device B reported an r2=0.96, with averages of 300.6±3.7, 341.4±7.9, and 376.8±5.1 mOsm/L, and CVs of 1.2%, 2.3%, and 1.4%, respectively. Device C reported an r2=0.03, with averages of 336.4±21.5, 342.0±20.7, and 345.7±22.0 mOsm/L, and CVs of 6.4%, 6.1%, and 6.4%, respectively. Conclusion In this randomized, masked, in vitro study, device A and device B had significantly better accuracy and precision in measuring osmolarity of contrived tear solutions of known target values compared to device C. Device C showed insufficient performance to accurately and precisely delineate osmolarity levels in the physiological range. Furthermore, in vivo studies would be required to compare performance in human subjects.

Comparison of Femtosecond Laser-Enabled Descemetorhexis and Manual Descemetorhexis in Descemet Membrane Endothelial Keratoplasty

Purpose: To introduce a novel method to perform descemetorhexis in Descemet membrane endothelial keratoplasty (DMEK) using the femtosecond laser and to compare it with Descemet membrane endothelial keratoplasty performed with manual descemetorhexis (M-DMEK). Methods: A retrospective medical chart review of 2 groups of patients who underwent DMEK surgery combined with cataract surgery secondary to Fuchs corneal endothelial dystrophy and cataract: 17 patients underwent femtosecond laser-enabled descemetorhexis Descemet membrane endothelial keratoplasty (FE-DMEK) and 89 patients underwent DMEK surgery with M-DMEK. Best spectacle-corrected visual acuity, endothelial cell density (ECD), graft detachment rate, and complications were compared. Results: Average age of the 106 patients (64 women and 42 men) was 68 ± 11 years. Postoperative best spectacle-corrected visual acuity was 0.19 ± 0.13 logarithm of the minimum angle of resolution in the FE-DMEK group and 0.35 ± 0.48 logarithm of the minimum angle of resolution in the M-DMEK group (P = 0.218). One day after surgery, there were no significant graft detachments in the FE-DMEK group, compared with 20% graft detachment rate in the M-DMEK group (P = 0.041). Rebubbling was performed in 17% of eyes in the M-DMEK group compared with none in the FE-DMEK group (P = 0.066). The mean endothelial cell count in the FE-DMEK and M-DMEK groups at 6 months after surgery were 2105 ± 285 cells per square millimeter (24% cells loss) and 1990 ± 600 cells per square millimeter (29% cells loss), respectively (P = 0.579). Conclusions: FE-DMEK shows efficacy similar to that of M-DMEK with apparently less graft detachment and reduced need for rebubbling.

Simple Preoperative Ink Test as a Novel Adjunct to Intrastromal Keratopigmentation for Post-laser Peripheral Iridotomy Dysphotopsias

Purpose: To describe a simple preoperative ink test as a novel adjunct to intrastromal keratopigmentation for post-laser peripheral iridotomy (LPI) dysphotopsias. Methods: A surgical marking pen is applied to the area over a peripheral iridotomy before intrastromal keratopigmentation. The patient can then assess whether there is any improvement in their symptoms of dysphotopsias. Manual intrastromal keratopigmentation can then be performed using a crescent blade into the clear cornea at 50% depth and tunneled centrally to create a pocket ensuring that the peripheral iridotomy is fully occluded. The crescent blade is coated with an alcohol-based commercially available black tattoo pigment, and the pocket is filled. Results: We have used the preoperative ink marker test on 5 eyes in patients with post-LPI (4 temporal and 1 superior) dysphotopsias before performing intrastromal keratopigmentation, with good patient satisfaction. Patients report immediate symptomatic relief after the procedure. This ink marking technique can also be extended to help identify which iris defect is symptomatic in patients with multiple iris defects. Conclusions: The preoperative ink test before intrastromal keratopigmentation is a novel adjunct to the treatment of post-LPI dysphotopsias.

Peripheral Blunt Dissection: Using a Microhoe-Facilitated Method for Descemet Membrane Endothelial Keratoplasty Donor Tissue Preparation

Purpose: To describe a modified technique for Descemet membrane donor tissue preparation that facilitates the original Melles stripping technique. Methods: Descemet membrane is prepared using a Rootman/Goldich modified Sloane microhoe, using a blunt instrument as opposed to a sharp blade or needle and begins dissection within the trabecular meshwork. The trabecular tissue is dissected for 360 degrees, and then Descemet membrane is stripped to approximately 50%. A skin biopsy punch is then used to create fenestration in the cornea, which is used to mark an “F.” on the stromal side of Descemet membrane to aid in orientation of the graft. Trephination of the membrane is then performed and stripping is completed. The tissue is stained with 0.06% trypan blue and aspirated into an injector for insertion into the anterior chamber. Results: Before converting to the technique described, 5 of 75 (6.7%) tissues were wasted and 7 of 75 (9.3%) tissues with radial tears were salvaged for use. Since converting to the new technique, only 1 of 171 (0.6%) (P = 0.01) tissues was wasted and 7 of 171 (4.1%) (P = 0.2) tissues with radial tears were salvaged. Conclusions: The peripheral blunt dissection technique offers an improvement over the technique originally described by Melles et al, as the incidence of tissue wastage and tears is lower, it is easy to learn, has low stress, and is reproducible. Combining this with a stromal surface letter mark ensures correct orientation of the tissue against the corneal stroma of the recipient.

Systemic immunosuppression in limbal stem cell transplantation: best practices and future challenges

The objective of this study was to evaluate systemic immunosuppression regimens used for patients undergoing ocular surface stem cell transplantation, including their benefits and adverse effects in the adjunctive management of limbal stem cell deficiency (LSCD). A systematic literature review was conducted using the MEDLINE and EMBASE databases (1980-2015). Data were collected on surgical intervention(s), type of immunosuppressive agent(s), duration of immunosuppression, percentage with stable ocular surface at last follow-up, mean follow-up time, and demographics. Data were also collected on adverse ocular and systemic outcomes. Sixteen reports met the inclusion criteria. There were no randomized controlled studies. Three studies were noncomparative prospective case series, whereas the majority were retrospective case series. Bilateral severe LSCD was the most common disease (50%), and keratolimbal allograft was the most common intervention (80%). Immunosuppressive regimens showed a progression from early studies using oral cyclosporine to later studies using combinations of mycophenolate mofetil and tacrolimus. Most studies included a course of high-dose systemic corticosteroids. For patients adherent to long-term systemic immunosuppression, stable ocular surface rates of 70%-80% at last follow-up were reported. Adverse effects included hypertension, diabetes mellitus, and biochemical abnormalities managed with pharmacotherapy or discontinuation of offending agents. There were no cases of mortality related to immunosuppression. However, the current literature does not elucidate which immunosuppressive regimen is most efficacious for different categories of LSCD or graft types. Evidence-based guidelines for systemic immunosuppression in limbal allograft therapy would benefit from randomized controlled and/or additional prospective studies. Long-term immunosuppression would benefit from close collaboration between ophthalmologists and transplant specialists to individualize treatments.

Topography-Guided Photorefractive Keratectomy in the Treatment of Corneal Scarring.

PURPOSE To report the outcome of topography-guided photorefractive keratectomy (TG-PRK) in the treatment of patients with corneal scarring. METHODS A retrospective, interventional case series including 6 eyes of 6 patients with corneal scarring and irregular astigmatism who underwent TG-PRK. The etiologies for scarring were: infectious corneal ulcers, foreign body trauma, LASIK flap buttonhole, and lamellar keratoplasties performed to correct corneal perforation secondary to corneal melting. Main outcome measures were corrected distance visual acuity, uncorrected distance visual acuity, manifest refraction, and corneal regularity on topography maps. RESULTS Average age was 56.5 ± 19.6 years and average follow-up time was 14.8 ± 6.1 months. Three patients had corneal scarring with cataract and underwent TG-PRK to achieve sufficient regularization of corneal astigmatism to enable the implantation of a toric intraocular lens (IOL). The three remaining patients had TG-PRK performed to improve visual acuity, and all had improvement in uncorrected (improvement between one and three Snellen lines) and corrected (improvement between two and three Snellen lines) distance visual acuity. There were no intraoperative or postoperative complications and no loss of visual acuity. CONCLUSIONS The use of TG-PRK for corneal scarring may improve visual acuity in selected cases, obviate the need for keratoplasty in some cases, and facilitate toric IOL implantation in some cases. [J Refract Surg. 2017;33(9):639-644.].