Artificial Cornea: Past, Current, and Future Directions.

Corneal diseases are a leading cause of blindness with an estimated 10 million patients diagnosed with bilateral corneal blindness worldwide. Corneal transplantation is highly successful in low-risk patients with corneal blindness but often fails those with high-risk indications such as recurrent or chronic inflammatory disorders, history of glaucoma and herpetic infections, and those with neovascularisation of the host bed. Moreover, the need for donor corneas greatly exceeds the supply, especially in disadvantaged countries. Therefore, artificial and bio-mimetic corneas have been investigated for patients with indications that result in keratoplasty failure. Two long-lasting keratoprostheses with different indications, the Boston type-1 keratoprostheses and osteo-odonto-keratoprostheses have been adapted to minimise complications that have arisen over time. However, both utilise either autologous tissue or an allograft cornea to increase biointegration. To step away from the need for donor material, synthetic keratoprostheses with soft skirts have been introduced to increase biointegration between the device and native tissue. The AlphaCor™, a synthetic polymer (PHEMA) hydrogel, addressed certain complications of the previous versions of keratoprostheses but resulted in stromal melting and optic deposition. Efforts are being made towards creating synthetic keratoprostheses that emulate native corneas by the inclusion of biomolecules that support enhanced biointegration of the implant while reducing stromal melting and optic deposition. The field continues to shift towards more advanced bioengineering approaches to form replacement corneas. Certain biomolecules such as collagen are being investigated to create corneal substitutes, which can be used as the basis for bio-inks in 3D corneal bioprinting. Alternatively, decellularised corneas from mammalian sources have shown potential in replicating both the corneal composition and fibril architecture. This review will discuss the limitations of keratoplasty, milestones in the history of artificial corneal development, advancements in current artificial corneas, and future possibilities in this field.

Confocal and Histological Features After Poly(Ethylene Glycol) Diacrylate Corneal Inlay Implantation.

PURPOSE: To evaluate the in vivo biocompatibility of photopolymerized poly(ethylene glycol) diacrylate (PEGDA) intrastromal inlays in rabbit corneas. METHODS: Sixty-three eyes of 42 New Zealand rabbits were included. Manual intrastromal pockets were dissected in 42 eyes. PEGDA inlays were obtained using a specifically designed photomask and were inserted in the intrastromal pocket of 21 eyes (inlay group); the remaining 21 right eyes did not receive any implant (pocket-only group). Twenty-one eyes with no intervention were used as controls. In vivo confocal microscopy (IVCM) was performed at every visit. After 2 months, rabbits were sacrificed and corneas removed for histological analysis. RESULTS: Corneas remained clear in all but two animals, and five cases of corneal neovascularization were seen (P = 0.2). Inlays remained stable without evidence of lateral or anterior migration, and no other complications were observed. No changes in anterior and posterior keratocyte density (P = 0.3 and P = 0.1, respectively) or endothelial cell density (P = 0.23) were observed between groups during the study time by IVCM. On pathology samples, thinning of the epithelium over the inlay area and epithelial hyperplasia over the edges were observed. A polygonal empty space with no evidence of PEGDA hydrogel within the midstroma was seen in the inlay group. Keratocytes were normal in shape and number in the vicinity of the PEGDA implant area. CONCLUSIONS: Photopolymerized PEGDA intrastromal inlays have shown relatively good safety and stability in rabbit corneas. Inlays were biostable in the corneal environment and remained transparent during follow up. TRANSLATIONAL RELEVANCE: The investigated PEGDA is promising for the development of biocompatible intrastromal implants.

Bilateral Retrobulbar Optic Neuropathy Associated With Golimumab.

We report the first documented case of retrobulbar optic neuropathy associated with golimumab. A 48-year-old man was admitted with a 3-week history of progressive visual loss of his left eye. He had received a second infusion of golimumab for ankylosing spondylitis 10 days before admission. A magnetic resonance imaging scan showed enhancement of both optic nerves and visual evoked potentials were consistent with demyelinating bilateral optic neuropathy, although visual acuity drop in the right eye could not be determined because of deep amblyopia. No improvement was observed after golimumab dechallenge or corticosteroid treatment. Demyelinating complications related to treatment with tumor necrosis factor alpha inhibitors (TNFAI) have been previously described. Golimumab, a fully human monoclonal antibody, is the most recently developed TNFAI and thus, fewer adverse effects have been reported. Further studies should be developed to elucidate if variability in golimumab's pharmacokinetics or TNF receptor binding affinity could explain different safety profiles compared with other TNFAI.

Objective optical quality analysis using double-pass technique in pterygium surgery.

PURPOSE: To analyze objective optical quality changes after pterygium surgical excision using the Optical Quality Analysis System. METHODS: Forty eyes with primary pterygium suitable for surgical treatment were included. Uncorrected distance visual acuity, corrected distance visual acuity (CDVA), objective scattering index (OSI), and cutoff frequency of the modulation transfer function (MTFcutoff) were recorded preoperatively and at 1 and 6 months postoperatively. Slit-lamp measurement of pterygium size was performed to classify them: small in group 1 and medium size/large in group 2. A paired comparative study of all data that included preoperative with 1-month results (comparison A), preoperative with 6-month results (comparison B), and 1 month with sixth-month results (comparison C) was performed. RESULTS: In global analysis, uncorrected distance visual acuity and OSI showed significant changes in comparison A, all parameters in comparison B, and CDVA, OSI, and MTFcutoff in comparison C. When subdividing into groups, in group 1, there was significant improvement between preoperative uncorrected distance visual acuity value and those at 1 and 6 months. Significant improvement in CDVA, OSI, and MTFcutoff values were observed in comparisons B and C. In group 2, MTFcutoff values significantly improved in comparisons B and C. The comparison of mean values between each group at each evaluation showed a lower value for MTFcutoff at 1 month after surgery. A comparative analysis of the evolution between both groups based on pterygium size did not reveal significant differences. CONCLUSIONS: Pterygium can undermine visual quality, and its excision provides significant improvement even at 6 months after surgery. Optical Quality Analysis System proved useful for postoperative outcomes.