Henry D. Perry

Round and Oval Cones in Keratoconus

In advanced keratoconus, there are two cone types. The more common round or nipple shaped cone is limited in diameter but may reach any degree of conicity. The cone center lies mostly in the lower nasal quadrant. The oval or sagging cone, is often larger and lies more commonly in the inferotemporal quadrant close to the periphery. The oval cone is usually associated with more episodes of corneal hydrops, scarring and difficulty in fitting contact lenses. Histopathologic review of 23 cases (10 round, 13 oval), revealed that the oval group had more breaks in Bowmans membrane, 10.1 versus 5.0, (P smaller than 0.01), and a tendency toward greater pannus formation with more ruptures in Descemets membrane. We hope this clinicopathologic correlation may allow a more logical approach to patient care based on recognizing two different cone types in advanced keratoconus.

Failed descemet-stripping automated endothelial keratoplasty grafts: a clinicopathologic analysis.

PURPOSEnTo describe the clinicopathologic findings in failed Descemet-stripping automated endothelial keratoplasty (DSAEK) grafts.nnnDESIGNnRetrospective, interventional case series.nnnMETHODSnnnnSETTINGnNew York Eye and Ear Infirmary.nnnSTUDY POPULATIONnTwenty-one patients with 22 failed DSAEK grafts treated between March 1, 2006 and February 1, 2008.nnnINTERVENTIONnRepeat DSAEK or penetrating keratoplasty were performed in the eyes with failed grafts. All failed grafts were examined histopathologically.nnnMAIN OUTCOME MEASURESnHistopathologic parameters studied in failed DSAEK grafts included endothelial cell count, interface characteristics, retrocorneal membrane formation, inflammation, and immunoreactivity for herpes simplex virus type 1 (HSV-1) antigen.nnnRESULTSnDSAEK failure was strongly associated with postoperative lenticle dislocation. Graft failure was primary in 19 DSAEKs and secondary to rejection, eccentric trephination with epithelial ingrowth, or bacterial infection in the remaining 3. All failed grafts demonstrated endothelial hypocellularity and stromal edema. Additional findings included stromal inflammation (68%), interface fibrosis (50%), retrocorneal membrane (36%), unplanned retention of Descemet membrane (14%), immunoreactivity for HSV-1 (14%), paucicellular stroma (14%), and uneven trephination with epithelial ingrowth (5%).nnnCONCLUSIONSnMost DSAEK failures are secondary to endothelial cell loss. Other contributing factors include interface fibrosis, retrocorneal membrane formation, retained host Descemet membrane, uneven trephination, epithelial ingrowth, graft rejection, and infection.

Systemic Tetracycline Hydrochloride as Adjunctive Therapy in the Treatment of Persistent Epithelial Defects

Recent evidence shows tetracyclines have anticollagenolytic activity that may be clinically effective in disease treatment. This led us to use systemic tetracycline (oral tetracycline hydrochloride 1 g daily divided into 4 doses) as adjunctive therapy in treating 18 patients with persistent corneal epithelial defects. Fourteen of 18 patients healed their defects; within 48 hours (9 patients) and within two weeks (the other 5 responding patients). Two patients showed no effect and two showed disease progression.

A Clinicopathologic Study of Contact-Lens-Related Keratoconus

A patient, initially examined at the age of 16 years and monitored for almost two decades, had corneal warpage and keratoconus associated with contact lens wear. Although the patient was advised repeatedly of the risk of continued contact lens use, she persisted. Contact-lens corrected visual acuity continued to deteriorate in the left eye (from 20/20 to 20/200) and keratometric readings continued to increase (from 43.50/44.12 to 56/59). The patient eventually required a corneal transplant in the left eye because of advanced keratoconus. The host button was subjected to light and electron microscopy, which disclosed keratoconus of the round cone type. Spectacle-corrected visual acuity was 20/20 18 months postoperatively.

NIR laser tissue welding of in vitro porcine of cornea and sclera tissue

In this study, an NIR fiber laser with an eye safe wavelength of 1.455 μm was used to successfully weld in vitro porcine cornea and sclera tissue. The emission wavelength overlaps an absorption band of water. The laser system was used in combination with a motorized translational system and shutter to control the laser exposure on the tissue being welded. Different welding conditions were analyzed for the porcine cornea and sclera. The welded tissues were examined using histopathology and tensile strength analysis. The NIR welding technique provides strong, full thickness welds and does not require the use of extrinsic dyes, chromophores, or solders. The NIR laser system used in this study can effectively weld cornea and sclera tissue, and this laser tissue welding (LTW) methodology typically causes minimal disruption of tissue, and thus, avoids opacities and irregularities in the tissue which may result in decreased visual acuity.

Chronic postoperative endophthalmitis from Staphylococcus aureus

ABSTRACT We recently treated a patient with chronic postoperative endophthahnitis caused by Staphylococcus aureus, which usually presents with a fulminant clinical course. Because of the chronic course, the initial treatment was high dose steroids followed by lensectomy and vitrectoiny. However, this was not effective, and intravitreal antibiotics and steroids were ultimately required. We now recommend that in patients with chronic postoperative inflammation unresponsive to high dose steroids, intraocular cultures followed by injection of intraocular antibiotics be considered.

Superficial Reticular Degeneration of Koby

A 36-year-old white man with congenital ichthyosis and a history of a posterior uveitis beginning at age 8 presented with an unusual corneal opacity. At age 26 bilateral central corneal opacities were noted consisting of fine interlacing white lines forming a reticulum at the level of Bowmans membrane. A faint brown background tint of the basal epithelium was also present. Over the next 10 years the opacity progressed only slightly, with some mild superficial scarring of the underlying corneal stroma. The visual acuity remained good. This corneal pattern appeared virtually identical to the superficial reticular degeneration of Koby. As described by Koby in 1927, this rare corneal degeneration is characterised as a painless, slow, progressive development of a central fine, white reticulum at the level of Bowmans membrane. This rare corneal degeneration probably represents an atypical form of band keratopathy.

In vitro NIR laser tissue welding of porcine ocular tissues

In this study, 72 different combinations of laser welding parameters were compared for their effectiveness in welding ocular tissue. The laser employed in the welding system was a near infrared (NIR) erbium fiber laser with a wavelength of 1.455 μm . The laser system used a motorized translational stage and shutter to control the laser exposure of the tissue being welded. The emission wavelength of the laser in the NIR range corresponds to one of the lesser absorption bands of water. Parameters of the laser welding system that could be changed to allow a more effective distribution of the laser energy and therefore management of thermal energy included: the number and kinds of intricate offset patterns of light on or around the incision, the number of lines per pattern, the power level, the speed of the laser beam movement over the tissues, the spot size, dwell time and the focus plane of the light beam in the tissue. Histopathology was used as an endpoint indication of the effects that the various sets of welding parameters had on the welded tissues. Standard Hematoxylin and Eosin stain and Sirius Red F3B (Direct Red 80) in combination with polarization microscopy were used to stain and visualize the welded ocular tissue. Paradoxically, the best cornea welds quantified using histopathology occurred with fluence of 4,500 mJ/cm2 or less while the corneal welds exhibiting the strongest tensile strengths, but most tissue damage had a delivered fluence above 7,000 mJ/cm2. The best histological representatives of welded corneas had an average delivered fluence of 2,687 mJ/cm2 and an irradiance of 14 W/cm2. Using the properly determined parameters, the NIR erbium fiber welding system provided full thickness welds without the requirement of extrinsic dyes, chromophores, or solders. The NIR laser system with the appropriately developed parameters can be used effectively to weld ocular tissues.

Optimization of near-infrared laser tissue welding of porcine cornea: a Monte Carlo-aided dosimetry study

Monte Carlo simulations were performed to delineate the role of local fluence rates and absorption in histologic success and tensile strength analysis of laser welding of ocular corneal tissue using an erbium fiber laser system operating at 1455nm wavelength. Porcine cornea was used for in vitro welding, while varying power, scan time, and irradiance. Immediate histologic analysis was performed, as well as tensile strength studies. Simulations were performed using MCML code, with a total of 109 photons started. CONV code was used to convolve the output from MCML for a flat photon beam of 80-800 μ focal spot size and power specified by the experiment. The absorption coefficient, μa, was assumed to reflect that of water, 28.6 cm-1. The scattering coefficient, μs, and anisotropy factor, g, were both neglected due to the poor scattering capabilities of water in the wavelength of the laser beam. Fluence rates were determined and were within 0.3%-4% of surface dose calculations for a beam diameter of 80 μ. Interactive Data Language (IDL) was used to sum the dose for one convolved beam to an experiment with multiple scans across the porcine cornea. Achieving optimal usage of the laser system requires maximal use of the variables (power, scan patterns, scan time, irradiance) available to use, and the correlation between Monte Carlo-aided dosimetry and the histopathological and tensile strength studies was performed. Optimal parameters for use in this 1455 nm laser system can be studied, and will allow users the ability to predict histology scores of welding success and tissue injury based on absorption values. These results can refine our experience with laser tissue welding of porcine cornea and aid in determining optimal delivered dose for successful tissue apposition and minimal adverse thermal heating.