Temporary Pupil Scaffolding Technique for Managing Positive Vitreous Pressure and Impending IOL and Vitreous Extrusion During Penetrating Keratoplasty.

PURPOSE: Positive vitreous pressure (PVP) secondary to intraoperative acute hypotony during penetrating keratoplasty can result in extrusion of the intraocular lens and vitreous. Currently described techniques are difficult or impossible to apply intraoperatively when positive vitreous pressure is noticed in an "open sky" situation after excision of the host corneal button. METHODS: We describe a technique where pupil scaffolding is used to prevent intraocular lens or crystalline lens extrusion by simply closing the pupil with a temporary suture that holds the retropupillary contents back. Once the eye is thus stabilized, the donor cornea is sutured rapidly after which the pupillary knot is cut and removed using microscissors and microforceps. RESULTS: Five patients undergoing penetrating keratoplasty under peribulbar anesthesia underwent this technique after experiencing PVP after host corneal button excision. PVP was successfully controlled in all 5 patients, and the optical grafts remained clear in the postoperative period. CONCLUSIONS: Temporary pupillary scaffolding can help control PVP and prevent ocular content extrusion during PKP surgeries.

Customized corneal allogenic intrastromal ring segments (CAIRS) for keratoconus with decentered asymmetric cone.

Corneal allogenic intrastromal ring segments (CAIRS) refer to the intracorneal placement of fresh, unprocessed, processed, preserved, or packaged allogenic rings/segments of any type/length. We described uniform-thickness CAIRS previously. We now describe a new technique of customized CAIRS to personalize the flattening effect as per individual topography. A prospective interventional case series of patients with pericentral/ paracentral decentered cones and gradation of keratometry with one side steeper than the other was conducted. Individually customized tapered CAIRS with variable volume, arc length, taper length, and gradient of taper were implanted. In total, 32 eyes of 29 patients with at least 1-year follow-up were included. Special double-bladed trephines and a CAIRS customizer template allowed the creation of individually customized CAIRS. Mean uncorrected distance visual acuity (UDVA) and spectacle-corrected distance visual acuity improved from 0.22 to 0.47 (P = 0.000) and from 0.76 to 0.89 (P = 0.001), respectively. Significant improvement was seen in K1, K2, Km, Kmax, topographic astigmatism, Q-value, sphere, cylinder, spherical equivalent, Root Mean Square (RMS), Higher Order Aberrations (HOA), and vertical coma (P < 0.01, 0.05). There was no significant change in the width or height of CAIRS between 1 month and last visit on anterior-segment optical coherence tomography. Five eyes continued to remain at the same UDVA, 27 eyes had at least 2 lines, and 13 eyes had at least 3 or more lines improvement in UDVA. The maximum improvement in UDVA was 7 lines. A significant difference in flattening was obtained at different zones across the tapered CAIRS. Thus, differential flattening was achieved across the cone based on the customization plan. Personalized customization was possible for each cornea, unlike limited models of progressive-thickness synthetic segments. Allogenic nature, greater customizability, efficacy, and absent need for large inventories are advantages compared to synthetic segments.