Joshua H. Hou

The gel state of the vitreous and ascorbate-dependent oxygen consumption: relationship to the etiology of nuclear cataracts.

OBJECTIVE To investigate the rate and mechanism of oxygen consumption by the vitreous. METHODS Oxygen consumption was measured with a microrespirometer. Vitreous ascorbate was measured spectrophotometrically and by gas chromatography-mass spectrometry. Vitreous degeneration was related to the rate of oxygen consumption and ascorbate concentration in samples obtained during vitrectomy. RESULTS Prolonged exposure to oxygen or treatment with ascorbate oxidase eliminated oxygen consumption by the vitreous. Adding ascorbate restored oxygen consumption. Oxygen consumption persisted after boiling or treating the vitreous with the chelating agents EDTA and deferoxamine. In patients undergoing retinal surgery, liquefaction of the vitreous and previous vitrectomy were associated with decreased ascorbate concentration and lower oxygen consumption. CONCLUSIONS Ascorbate in the vitreous decreases exposure of the lens to oxygen. The catalyst for this reaction is not known, although free iron may contribute. The gel state of the vitreous preserves ascorbate levels, thereby sustaining oxygen consumption. Vitrectomy or advanced vitreous degeneration may increase exposure of the lens to oxygen, promoting the progression of nuclear cataracts. CLINICAL RELEVANCE Determining how the eye is protected from nuclear cataracts should suggest treatments to reduce their incidence.

Retroprosthetic Membrane and Risk of Sterile Keratolysis in Patients With Type I Boston Keratoprosthesis

PURPOSE To evaluate whether retro-backplate retroprosthetic membrane is correlated with risk of melt in patients with a type I Boston Keratoprosthesis (KPro). DESIGN Retrospective, observational case series. METHODS Study of 50 eyes of 47 patients with type I Boston KPro and postoperative anterior segment optical coherence tomography (AS OCT) imaging performed at the University of Illinois at Chicago. Main outcome measures were presence of retro-backplate membrane and development of melt requiring explantation. For eyes with melt, membrane thickness was measured using the AS OCT images obtained at the last visit before melt occurred. For eyes without melt, the last available AS OCT images were used for measurement. RESULTS AS OCT evidence of a retro-backplate membrane was observed in 100% of eyes that melted and in 34.1% of eyes that did not (P = .0034; risk ratio, 2.9; 95% confidence interval, 1.9 to 4.4). Retro-backplate membrane thickness in the melt group was 278 μm versus 193 μm in the nonmelt group (P = .025). CONCLUSIONS The retro-backplate portion of a retroprosthetic membrane is to be differentiated from the retro-optic portion seen at the slit lamp. The retro-backplate membrane as shown by AS OCT imaging is correlated with an increased risk of sterile keratolysis, possibly because of impedance of nutritional support from the aqueous humor. Further studies are needed to better standardize the AS OCT measurements of retro-backplate membranes as well as to identify early interventions to prevent progression of thin membranes once identified on AS OCT.

Outcomes of boston keratoprosthesis implantation for failed keratoplasty after keratolimbal allograft

Purpose: To evaluate factors that contribute to keratoplasty failure after keratolimbal allograft (KLAL) and report the outcomes of Boston keratoprosthesis type I (KPro) as salvage therapy. Methods: Retrospective noncomparative case series of 7 eyes in 7 consecutive patients with ocular surface disease and limbal stem cell deficiency treated with KPro after failed KLAL. Mechanisms of graft failure, KPro device retention rate, and preoperative and postoperative best-corrected visual acuities were studied. Results: In the studied cohort, keratoplasty graft failure occurred at an average of 9.9 months (range, 1–17 months) after KLAL. Among the 7 eyes reviewed, 4 had tube shunts, 3 of which contributed directly to endothelial graft failure. One eye failed due to fungal keratitis, 1 eye failed due to immune-mediated endothelial rejection, and 2 eyes failed due to recurrent surface disease. During an average follow-up of 585 days (19.5 months) after KPro, best-corrected visual acuity improved from a median of counting fingers CF@2ft (range, hand motions to 20/400) to a median of 20/400 (range, CF@3ft to 20/25). There was 85.7% (6 of 7) retention of implanted devices at the last follow-up, with 1 eye requiring repeat KPro for corneal melt and implant extrusion after abrupt cessation of immunosuppression. Conclusions: Despite successful KLAL outcomes and systemic immunosuppression, patients who undergo ocular surface reconstruction with KLAL are still at risk for subsequent keratoplasty failure. Keratoprosthesis is a viable salvage therapy for visual rehabilitation in these patients. Adequate immunosuppression is important in postoperative management of these patients.

Histopathological and Immunohistochemical Analysis of Melt-Associated Retroprosthetic Membranes in the Boston Type 1 Keratoprosthesis

IMPORTANCE Retroprosthetic membrane (RPM) formation is the most common complication associated with the Boston type 1 keratoprosthesis and has been associated with corneal melt. OBJECTIVE To identify the histological and immunohistochemical characteristics of RPMs associated with corneal melt. DESIGN, SETTING, AND PARTICIPANTS Observational histopathological case series at a tertiary eye care referral center among patients who underwent Boston type 1 keratoprosthesis explantation because of donor corneal melt at the Illinois Eye and Ear Infirmary between January 1, 2011, and January 1, 2012. EXPOSURES Seven RPM specimens from 7 eyes were stained with hematoxylin-eosin, cytokeratin 7, cytokeratin AE1/3, smooth muscle actin, vimentin, and CD34. Light microscopy was used to evaluate specimens for inflammation and epithelial ingrowth. XY-karyotyping using fluorescence in situ hybridization was performed on 4 specimens with known donor-recipient sex mismatch. MAIN OUTCOMES AND MEASURES Histological and immunohistochemical characteristics of RPMs. RESULTS Inflammatory cells were present in 4 of 7 RPMs. In 3 of 4 sex-mismatched specimens, tissue XY-karyotyping of the RPM interphase cells was consistent with the host sex karyotype. The fourth specimen showed a mixture of recipient-type and donor-type cells. CONCLUSIONS AND RELEVANCE Melt-associated RPMs show variable degrees of inflammation. Most membranes seem to originate from a proliferation of host cells, but donor tissue may contribute in some cases.

Relative Incidence of Blepharoptosis Subtypes in an Oculoplastics Practice at a Tertiary Care Center

Abstract Purpose: In patients referred with blepharoptosis, the possibility of an underlying systemic cause for their ptosis can warrant a more detailed evaluation. The purpose of this study is to determine both the incidence and demographic characteristics associated with different types of ptosis in patients referred to the oculoplastics division at a tertiary care center. Methods: A retrospective chart review was performed on all patients referred to the oculoplastics division between 2007 and 2010. Final etiology for each patient’s ptosis was determined based on history, standard eyelid measurements, and ancillary testing. Based on etiology, ptosis was categorized as aponeurotic, neurogenic, myogenic, traumatic, congenital, or mechanical. Demographics, including median age and sex were analyzed for patients in each category of ptosis. Results: Of the 251 patients, aponeurotic ptosis was the most common type of ptosis (60.2%), followed by traumatic (11.2%), congenital (10.4%), mechanical (8.8%), neurogenic (5.6%), and myogenic (4.0%). Of the neurogenic group, 35.7% of patients had cranial nerve 3 (CN 3) palsy, 28.6% had myasthenia gravis, 14.3% had aberrant regeneration, and 7.1% had Horner’s syndrome. Thirty percent of the myogenic group had chronic progressive external ophthalmoplegia (CPEO). The congenital group had the youngest median age (10.5 years), yet the aponeurotic group had the oldest (62 years). Conclusions: A significant proportion of patients referred with ptosis had more serious conditions such as neurogenic or myogenic ptosis. Thus, clinicians should maintain a high degree of suspicion and thoroughly evaluate all patients with ptosis in order to properly assess for underlying systemic associations.

Safety of femtosecond laser-assisted cataract surgery performed by surgeons in training.

Femtosecond laser-assisted cataract surgery has grown in popularity among ophthalmologists as a novel technique with the potential to reduce phacoemulsification energy requirements.1,2 However, early adoption of femtosecond laser-assisted cataract surgery by experienced cataract surgeons has been associated with a significant learning curve.3 Roberts et al. reported higher complication rates in the first 200 cases of femtosecond laser-assisted cataract surgery compared to 1,300 subsequent cases at a single high-volume practice.3 Given the challenges faced by experienced surgeons adopting femtosecond laser-assisted cataract surgery, it is unclear whether it can be safely performed by residents in training. We describe our experience with incorporating femtosecond laser-assisted cataract surgery in resident and fellow surgical training. After receiving Institutional Review Board approval, we performed a retrospective case–control study of resident and fellow outcomes with femtosecond laserassisted versus manual cataract surgery. All cataract surgeries performed at our institution from June 2012 to September 2013 by third-year residents and fellows with no prior femtosecond laser-assisted cataract surgery experience were identified. Cases performed without a femtosecond laser were included as manual cases. Cases in which wound construction, anterior capsulotomy, and lens fragmentation were performed using the LenSx femtosecond laser platform (Alcon Laboratories, Inc., Fort Worth, TX) were included as femtosecond laser-assisted cases. Cases were excluded if there was no documentation of intraoperative phacoemulsification parameters or if the case was not staffed by a corneal specialist experienced in femtosecond laser-assisted cataract surgery. Complications and phacoemulsification parameters, including phacoemulsification times, cumulative dissipated energy, aspiration time, and irrigation fluid use were compared between femtosecond laser-assisted and manual cases using a t test. In total, 62 femtosecond laser-assisted and 128 manual cataract surgery cases met inclusion criteria. There was no statistical difference in mean age (P = .12) or cataract grade (P = .31) between the two groups. Successful docking was achieved in 96.8% of eyes scheduled for femtosecond laser-assisted cataract surgery. Attending assistance was required in 46.8% of those eyes. Mean irrigation fluid use and cumulative dissipated energy were 22.5% and 38.2% higher, respectively, for manual cases (P ≤ .001). Total ultrasound, phacoemulsification, torsional, and aspiration times were all statistically higher in manual cases (P < .01) (Figure 1). In a sub-analysis excluding fellow cases, cumulative dissipated energy, fluid use, and phacoemulsification and torsional times remained statistically higher in manual cases despite the smaller sample size (P ≤ .03). In total, four posterior capsular tears and one burn wound occurred in the manual group. No posterior capsular tears or burn wounds occurred in the femtosecond laser-assisted group. This pilot study suggests that femtosecond laserassisted cataract surgery can be safely incorporated in resident and fellow surgical training. Given the high success rate (96.8%), docking was not a problem for residents performing femtosecond laser-assisted cataract surgery. Overall, the complication rate for manual cases (7.0%) was consistent with published rates for residents.4-6 However, surprisingly, fewer complica-

Intrastromal antifungal injection with secondary lamellar interface infusion for late-onset infectious keratitis after DSAEK

Purpose: The aim of this study was to report the successful medical management of 2 cases of late-onset endothelial keratoplasty–related stromal interface infections. Methods: All cases of endothelial keratoplasty–related infections treated with intrastromal antifungal injections were compiled. The following information was collected: demographic data, surgical indications, donor rim cultures, donor mate outcomes, clinical course, diagnostic tests, and clinical outcome. Results: Two cases of interface fungal keratitis diagnosed on clinical appearance and confocal microscopy were identified. Both patients refused to undergo further surgery and failed systemic and/or topical therapy. Each received 3 to 4 intrastromal injections, with secondary infusion into the graft–host interface, which resulted in the complete involution of their interface opacities. Conclusions: Intrastromal antifungal injection may be an effective alternative to surgical intervention in late-onset fungal Descemet stripping endothelial keratoplasty interface keratitis. Early treatment may preserve graft viability and result in a good visual outcome without the need for either penetrating keratoplasty or potential pathogen exposure to the anterior chamber.

Quantitative characterization of growth rate of an incidental deep dermoid cyst in a child using sequential magnetic resonance imaging

When orbital lesions are discovered incidentally, some have advocated observation given the slow-growing nature of deep dermoids; however, little has been published regarding the true growth potential of these tumors. We describe a case of an incidental deep orbital dermoid cyst in a 7.5-month-old girl with retinoblastoma. The cyst was monitored with five sequential magnetic resonance imaging studies of the orbit over 23 months with careful documentation of growth. The cyst was surgically removed without complication, and histopathology confirmed the diagnosis of dermoid cyst. This case represents the first published quantitative measurement of dermoid growth potential and highlights the need for close early monitoring in incidentally discovered cases.

Scanning Electron Microscopic Analysis of Biofilm Formation in Explanted Human Boston Type I Keratoprostheses

Purpose: To describe the morphological distribution of host tissue and microbial biofilms on the intraocular surfaces of Boston type I keratoprostheses (KPros) explanted because of corneal melt. Methods: Retrospective study of scanning electron microscopy (SEM) images from 4 explanted Boston type I KPros composed of polymethylmethacrylate and titanium. SEM images of KPro-associated ocular surfaces were reviewed for the presence of inflammatory cells, microbes, and/or biofilm formation. One sterile type I KPro was also imaged to serve as a (device only) control. Results: All 4 KPros were explanted because of culture-negative, clinically “sterile” donor corneal melt with impending KPro extrusion. In all cases, the rough, irregular surfaces of the device harbored more adherent corneal epithelium and stromacytes, inflammatory cells, and bacteria than the smooth, polished surface of the KPro optic. Two KPros showed not only evidence of prior bacterial colonization but marked biofilm formation. Conclusions: SEM images of explanted KPros explanted for “sterile” corneal melt demonstrated evidence of biofilm formation despite negative donor corneal cultures and the absence of clinical suspicion for infection. These results suggest that “sterile” corneal melt may be due to inflammatory host responses to low microbial burdens as seen in biofilms and/or released antigens after antibiotic-induced lysis. There was increased adherence of host tissue cells and microbial biofilms on the nonpolished surfaces of the KPro. Polishing the intraocular polymethylmethacrylate and titanium KPro surfaces may decrease microbial adhesion and biofilm formation in human subjects with KPros, but what impact this will have on rates of postoperative endophthalmitis is unknown.

Image-guided femtosecond laser–assisted cataract surgery in Peters anomaly type 2

UNLABELLED We describe a technique for image-guided femtosecond laser-assisted cataract surgery in a case of Peters anomaly type 2. The femtosecond laser technology enabled reliable construction of a complete capsulotomy despite central corneal opacification and a tented anterior capsule. Use of an image-guided femtosecond laser for cataract extraction in Peters anomaly type 2 is a safe method for removing these complex cataracts while preserving capsular and corneal integrity. FINANCIAL DISCLOSURE Dr. De la Cruz is a consultant to Alcon Surgical, Inc. No other author has a financial or proprietary interest in any material or method mentioned.