Corneal Collagen Cross-linking for Keratoconus in Pediatric and Developmentally Delayed Patients.

PURPOSE: Corneal cross-linking (CXL) is the standard of care in patients with keratoconus but presents unique challenges in children and developmentally delayed patients. We present our clinical decision-making algorithm, CXL surgical technique, and outcomes in these groups. METHODS: A retrospective chart review was undertaken at a tertiary referral center of all patients who underwent CXL for keratoconus at University of Pittsburgh Medical Center (UPMC) Children's Hospital of Pittsburgh between October 1, 2017, and April 1, 2021. Demographic information along with preoperative, intraoperative, and postoperative ophthalmic examination findings were collected. The main outcome measures were indications of CXL, postoperative complications, and visual acuity (VA). RESULTS: Forty-eight eyes of 34 patients [21 patients (30 eyes) with developmental delay (DD) and 13 patients (18 eyes) with no DD (NDD)] underwent epithelium-off, standard CXL. General anesthesia was used for CXL in all patients except for 3 with NDD. A temporary central tarsorrhaphy was performed in all patients with DD and 7 patients with NDD. The remaining got a bandage contact lens. There were no immediate postoperative complications. A trend toward improvement in VA was noted postoperatively. The mean logMAR VA (with habitual correction) was 0.67 preoperatively and 0.57 postoperatively (P = 0.3) in DD and 0.52 and 0.36, respectively (P = 0.13), in NDD. CONCLUSIONS: This retrospective review presents a technique for assessment and treatment of keratoconus in children and those with DD. Our technique ensures timely diagnosis and provides a safe method for CXL in these groups. Temporary central tarsorrhaphy is a well-tolerated option to reduce postoperative pain.

Technique for the Management of Extensive Ocular Surface Lipodermoid Involving the Cornea of Children.

PURPOSE: Ocular surface lipodermoids with corneal involvement may require surgical intervention; if deep, ocular surface reconstruction with lamellar corneal tissue or amniotic membrane may be needed. We describe a staged technique using autologous ipsilateral simple limbal epithelial transplantation. METHODS: After verifying sparing of Descemet membrane, the conjunctival portion of the lipodermoid was debulked in the first stage. Six weeks later, the corneal portion was excised, followed by autologous ipsilateral simple limbal epithelial transplantation to promote rapid reepithelialization of the residual stromal bed. Temporary tarsorrhaphy was used for patient comfort and to expedite ocular surface healing. RESULTS: Three eyes of 3 children with grade III large ocular surface lipodermoids that encroached the visual axis and hindered proper eyelid closure underwent surgery without complications. In all cases, the visual axis was cleared and eyelid closure was improved. At the last follow-up (mean 35.7 months, median 36.0 months), the bed of the original dermoid showed minimal haze in 1 case, while 2 eyes developed small pseudopterygium; best spectacle-corrected visual acuity improved from 20/200 to 20/70 in the first case, from fix and follow to 20/50 in the second case, and remained fix and follow in the last case, but this child had congenital hydrocephalus with severe developmental delay. CONCLUSIONS: This surgical technique is a promising option for children with grade III large ocular surface lipodermoids given its effectiveness in clearing the visual axis and in improving eyelid closure. Moreover, it does not require lamellar corneal transplantation or intervention to the fellow eye.

Biochemical and molecular alterations and potential clinical applications of biomarkers in keratoconus.

Keratoconus (KC) is a complex multifactorial corneal ectatic disorder, with disease onset commonly in the second-third decades significantly affecting quantity, quality of vision, and quality of life. Several pathways and factors such as eye rubbing, inflammatory, oxidative, metabolic, genetic, and hormonal among others have been studied in the last two decades. However, the management of KC is still based on a few "one-size fits all" approaches and is predominantly guided by topo/tomographic parameters. Consideration of the several novel factors which have the potential to be biomarkers in addressing several unanswered questions in the disease process could help in the better predictive ability of progression or vision loss and customization of treatment options. This article delves into the understanding of these novel factors or biomarkers based on the pathogenesis of KC and features a special focus on their potential clinical applications and their future role in personalized medicine.

Pythium insidiosum Keratitis: Past, Present, and Future.

Pythium insidiosum (PI) is an oomycete, a protist belonging to the clade Stramenopila. PI causes vision-threatening keratitis closely mimicking fungal keratitis (FK), hence it is also labeled as "parafungus". PI keratitis was initially confined to Thailand, USA, China, and Australia, but with growing clinical awareness and improvement in diagnostic modalities, the last decade saw a massive upsurge in numbers with the majority of reports coming from India. In the early 1990s, pythiosis was classified as vascular, cutaneous, gastrointestinal, systemic, and ocular. Clinically, morphologically, and microbiologically, PI keratitis closely resembles severe FK and requires a high index of clinical suspicion for diagnosis. The clinical features such as reticular dot infiltrate, tentacular projections, peripheral thinning with guttering, and rapid limbal spread distinguish it from other microorganisms. Routine smearing with Gram and KOH stain reveals perpendicular septate/aseptate hyphae, which closely mimic fungi and make the diagnosis cumbersome. The definitive diagnosis is the presence of dull grey/brown refractile colonies along with zoospore formation upon culture by leaf induction method. However, culture is time-consuming, and currently polymerase chain reaction (PCR) method is the gold standard. The value of other diagnostic modalities such as confocal microscopy and immunohistopathological assays is limited due to cost, non-availability, and limited diagnostic accuracy. PI keratitis is a relatively rare disease without established treatment protocols. Because of its resemblance to fungus, it was earlier treated with antifungals but with an improved understanding of its cell wall structure and absence of ergosterol, this is no longer recommended. Currently, antibacterials have shown promising results. Therapeutic keratoplasty with good margin (1 mm) is mandated for non-resolving cases and corneal perforation. In this review, we have deliberated on the evolution of PI keratitis, covered all the recently available literature, described our current understanding of the diagnosis and treatment, and the potential future diagnostic and management options for PI keratitis.

Corneal Biomechanics and Intraocular Pressure Following Scleral Lens Wear in Penetrating Keratoplasty and Keratoconus.

OBJECTIVE: To compare corneal biomechanics and intraocular pressure (IOP) in keratoconus and penetrating keratoplasty eyes before and after nonfenestrated scleral lens wear. METHODS: Twenty-three participants were enrolled, and 37 eyes were included in the analysis (11 penetrating keratoplasty and 26 keratoconus). A range of corneal biomechanical parameters and IOP were measured using the CORVIS ST before and after 8 hr of nonfenestrated scleral lens wear (Keracare, Acculens, Denver, CO). RESULTS: Before lens wear, penetrating keratoplasty eyes displayed significantly greater median values for central corneal thickness (97 µm thicker, P=0.02), IOP (3.89 mm Hg higher, P=0.01), and biomechanical parameter A2 length (0.48 mm longer, P=0.003) compared with keratoconic eyes. No significant changes in corneal biomechanical parameters or IOP were observed after scleral lens wear in either group (all P>0.05). CONCLUSION: Although nonfenestrated scleral contact lenses can induce a subatmospheric pressure after lens settling and compress tissue surrounding the limbus, no significant changes were detected in the corneal biomechanical parameters studied using CORVIS ST after scleral lens wear in eyes with penetrating keratoplasty and keratoconus.

The effect of scleral lenses on vision, refraction and aberrations in post-LASIK ectasia, keratoconus and pellucid marginal degeneration.

PURPOSE: To quantify the effect of a single scleral lens design on visual acuity and ocular higher-order aberrations in eyes with post-LASIK ectasia, keratoconus and pellucid marginal degeneration (PMD) that could not achieve satisfactory vision with spectacles or soft contact lenses. METHODS: Forty-six eyes of 28 participants fitted with diagnostic scleral lenses (KeraCare) were analysed, including 19, 15 and 12 eyes with post-LASIK ectasia, keratoconus and PMD, respectively. Corrected distance visual acuity (CDVA) and ocular aberrations were measured prior to lens wear and during lens wear after 60 min of settling. An i-Trace aberrometer was used to determine aberrations over a 4.5 mm diameter pupil. RESULTS: Before lens wear, the median (95% confidence interval) values across all groups were: CDVA 0.30 (0.30, 0.40) logMAR, spherical equivalent refraction -2.75 (-5.25, -2.12) D, cylindrical refraction 3.75 (2.50, 5.00) D, higher-order-root-mean-square error (HO-RMS) 0.90 (0.64, 1.03) µm and vertical coma co-efficient C(3,-1) -0.32 (-0.42, -0.12) µm. RMS coma of 0.52 (0.40, 0.74) µm was higher for the keratoconus group than for the other groups (p < 0.05). During lens wear, values improved considerably across all groups: CDVA 0.0 (0.0, 0.00) logMAR, spherical equivalent refraction -0.50 (-0.75, +0.50) D, cylindrical refraction 0.50 (0.00, 0.50) D, HO-RMS 0.32 (0.26, 0.42) µm and C(3,-1) +0.12 (+0.02, +0.19) µm (all p < 0.001 compared to pre-lens wear). While reduced significantly, RMS coma remained higher in the keratoconus group at 0.35 (0.31, 0.52) µm than in the post-LASIK ectasia and PMD groups at 0.17 (0.12, 0.21) µm and 0.07 (0.02, 0.46) µm, respectively (p < 0.05). CONCLUSIONS: The KeraCare scleral contact lens reduced ocular aberrations and improved visual acuity in patients with post-LASIK ectasia, keratoconus and PMD. The sign of vertical coma changed in keratoconus and PMD.

Scleral Lens Visual Rehabilitation of Sequential Bilateral Corneal Hydrops With Post-LASIK Ectasia.

ABSTRACT: This case report describes a unique presentation of bilateral sequential acute corneal hydrops that manifested several years after laser in situ keratomileusis. Initial management included anterior chamber perfluoropropane gas injection and corneal suturing. Longer-term visual rehabilitation involved the use of scleral lenses which significantly reduced lower- and higher-order ocular aberrations.

Repeatability of Orbscan III for anterior segment parameters in normal eyes.

PURPOSE: Assessment of repeatability of Orbscan III in measuring steep keratometry (sKm), flat keratometry (fKm), thinnest corneal thickness (TCT), anterior chamber depth (ACD), white-to-white diameter (WTW) and 3 mm and 5 mm zonal irregularity in healthy eyes. METHODS: In this prospective observatioanl study 100 eyes of 50 participants underwent three consecutive scans on Orbscan III by a single examiner with a gap of 5 minutes between scans. Statistical analysis was performed to assess the repeatability of sKm, fKm, TCT, WTW, ACD and parameters of 3- and 5 mm irregularity. Within subject standard deviation (Sw), coefficient of variation (CoV) and test retest variability (TRT) was calculated for the commonly used parameters. WERE THE MAIN OUTCOME MEASURES.: The repeatability of sKm, fKm, TCT, WTW, ACD, 3 mm and 5 mm zonal irregularity on Orbscan III. RESULTS: Total of 50 patients (25 male and 25 female) who fulfilled inclusion and exclusion criteria were assessed. sKm, fKm, TCT and WTW were found to have a TRT of 0.31, 0.29. 21.5 and 0.27, respectively, and the ICC values were found to be over 0.9, denoting high repeatability. Repeat measurements of parameters of irregularity and ACD were found to be statistically similar, again denoting similarity between repeat measurements. CONCLUSION: Orbscan III provides repeatable measurements of Sim-k, anterior chamber depth, thinnest corneal thickness, 3 mm and 5 mm zonal irregularity and white-to-white diameter in healthy eyes.

Scleral lens wear following penetrating keratoplasty: changes in corneal curvature and optics.

PURPOSE: Visual rehabilitation following penetrating keratoplasty is the primary indication for approximately 15% of all scleral lens fittings. Since corneal biomechanics are altered following penetrating keratoplasty, the aim of this study was to quantify changes in anterior corneal optics following short-term scleral lens wear in eyes with corneal grafts. METHODS: Scheimpflug images were obtained before and after a period of scleral lens wear (mean 6.3 ± 1.4 h), from eyes that had previously undergone penetrating keratoplasty (10 eyes of nine participants, mean age 31 ± 9 years). Corneal power and thickness data were examined over the central 6 mm, including regional analyses of the central (0-3 mm) and the mid-peripheral cornea (3-6 mm annulus) using customised software to deterime corneal power vectors M (best fit sphere), J0 (90/180 astigmatism) and J45 (45/135 astigmatism). Anterior corneal aberrations were extracted using corneal elevation data. RESULTS: Corneal power vector J45 increased following lens wear (by 0.22 ± 0.05 D, p = 0.003) across the central 6 mm, while M displayed regional variations following lens wear indicating larger changes further from the corneal centre (p = 0.004). The change in corneal power vector M was also correlated with the magnitude of central corneal swelling (r = 0.65, p = 0.04). The anterior corneal aberration terms of oblique astigmatism, hoirzontal coma, and spherical aberration also varied following lens wear (all p ≤ 0.01). The mean change in the corneal spherocylinder derived from the elevation data following lens wear was +0.14/-0.54 × 44 for a 6 mm corneal diameter. CONCLUSIONS: Clinically significant alterations in anterior corneal topography and higher order aberrations were observed following short-term scleral lens wear in eyes that had undergone penetrating keratoplasty. Spherocylindrical changes were approximately double the magnitude and more oblique in orientation compared to previous reports of healthy eyes. Changes in corneal power vector M may be related to epithelial corneal oedema.