Jonathan C. Song

Optical coherence tomography to assess intrastromal corneal ring segment depth in keratoconic eyes.

PURPOSE: To investigate intrastromal corneal ring segment depth with a high‐speed corneal optical coherence tomography (OCT) system. SETTING: Doheny Eye Institute, University of Southern California, Los Angeles, California, USA. METHODS: A prospective observational case series comprised 4 eyes of 4 patients receiving Intacs intrastromal corneal ring segments (Addition Technology, Inc.) for keratoconus. Optical coherence tomography (OCT) was performed between 7 days and 43 days after implantation. RESULTS: The slitlamp impression of intrastromal corneal ring segment implantation depth did not correlate well with OCT measurements (r2 = 0.68). The fractional implantation depth was correlated with several surgical variables using a stepwise multivariate regression model, and 2 statistically significant correlations were found. The position of the distal portions of the ring segments was shallower than that of the portion closer to the insertion site (P = .003). Segments placed in the inferior cornea (P = .008) experienced more distal shallowing. Shallower depth was associated with greater fractional anterior stromal compression (P = .04). CONCLUSIONS: Shallower placement of intrastromal corneal ring segments may result in more complications, such as epithelial–stromal breakdown and extrusion, because of the greater anterior stromal tensile strain. The distal and inferior portions of intrastromal corneal ring segments tended to be placed at a shallower depth. Optical coherence tomography provided precise measurement of ring segment depth and may help identify implants that pose a greater risk for depth‐related complications.

Refractive Surgery in Children: Treatment Options, Outcomes, and Controversies

PURPOSE To summarize the evolution of the treatment of pediatric refractive errors, with an emphasis on recent advancements in the use of refractive surgery to treat children. DESIGN Literature review. METHODS We searched MEDLINE (1950 through October 2007), the Cochrane library (December through October 2007), and the Cumulative Index for Nursing and Allied Health Literature (December 1982 through October 2007) for English language articles using the following search strategy with MeSH terms and key words: pediatric refractive errors and amblyopia, anisometropia, hyperopia, myopia, laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), laser epithelial keratomileusis (LASEK), excimer laser, refractive intraocular lens (IOL). We also searched the bibliographies of all identified articles. RESULTS No multicenter, long-term, controlled trial has been published on the use of refractive surgery in children. The current literature shows that LASIK, PRK, and LASEK show promising results in children with refractive amblyopia over the intermediate follow-up period. Corneal haze and myopic regression are the main complications, especially in very high myopia (> 12 diopters). In such patients with extremely high myopia, small studies have reported phakic IOLs or clear lens extraction with or without IOL implantation to be a useful alternative. CONCLUSIONS Refractive surgery is appropriate in children with severe anisometropia or bilateral high ametropia that is resistant to conventional therapy. More information is needed before pediatric refractive surgery can be widely adopted by the ophthalmic community. This could be achieved with a large, prospective, multicenter, randomized, controlled clinical trial.

Optical coherence tomography of clear corneal incisions for cataract surgery

PURPOSE: To study the architecture of clear corneal incisions for phacoemulsification cataract surgery using optical coherence tomography (OCT). SETTING: Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA. METHODS: This prospective study comprised 20 eyes of 20 patients 1 month after cataract surgery performed by 1 of 2 experienced surgeons. Temporal clear corneal single‐plane incisions were made with 3.0 mm metal keratomes. Each eye was scanned before and 1 month after surgery with a prototype high‐speed anterior segment OCT system (Carl Zeiss Meditec, Inc.). The OCT scans were repeated 3 times during the same visit. The length of the corneal incision, thickness of the cornea, and position of the incision (distance from external wound edge to scleral spur) were measured using a computer caliper. The angle of the incision relative to the corneal surface was then calculated. RESULTS: The mean corneal incision length was 1.81 mm ± 0.27 (SD), the mean corneal thickness at the incision was 747 ± 67μm, and the mean distance between the incision and the scleral spur was 1.46 ± 0.24 mm. The mean angle of the incision was 26.8 ± 5.5 degrees. The measurements were repeatable to within ±0.072 mm (pooled standard deviation) for the incision length, ±11 μm for the corneal thickness, and ±0.042 mm for the position of the incision. CONCLUSIONS: Optical coherence tomography allowed excellent evaluation of corneal incisions in cataract surgery postoperatively. Measurements of wound dimensions using OCT were highly repeatable.

High-speed optical coherence tomography for management after laser in situ keratomileusis

PURPOSE: To report applications of optical coherence tomography (OCT) in the management of laser in situ keratomileusis (LASIK) related problems. SETTING: Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA. METHODS: Five patients referred for LASIK‐related problems were enrolled in a prospective observational study. Clinical examination, ultrasound (US) pachymetry, Placido ring slit‐scanning corneal topography (Orbscan II, Bausch & Lomb), and high‐speed corneal OCT were performed. RESULTS: In cases of regression and keratectasia, OCT provided thickness measurements of the cornea, flap, and posterior stromal bed. Locations of tissue loss and flap interface planes were identified in a case with a recut enhancement complication. The information was used to determine whether further laser ablation was safe, confirm keratectasia, and manage complications. Optical coherence tomography measurements of central corneal thickness agreed well with US pachymetry measurements (difference 6.4 μm ± 11.7 [SD]) (P = .026), while Orbscan significantly underestimated corneal thickness (−67.5 ± 72.5 μm) (P = .17). CONCLUSIONS: High‐speed OCT provided noncontact imaging and measurement of LASIK anatomy. It was useful in monitoring LASIK results and evaluating complications.

Community opinions in the management of corneal ulcers and ophthalmic antibiotics: a survey of 4 states.

Objective: To evaluate the ophthalmic communitys current opinions of the management of bacterial keratitis and usage of the currently available ophthalmic antibiotics. Methods: An anonymous questionnaire was mailed to ophthalmologists in California, Florida, Illinois, and Missouri. The results were tabulated and analyzed statistically. Results: Six hundred twenty-nine usable questionnaires (10.3%) were returned. In the management of corneal ulcers, 42.2% of comprehensive ophthalmologists and 75.3% of cornea specialists perform Gram stains some of the time. A total of 73.3% of comprehensive ophthalmologists and 93.7% of cornea specialists perform corneal cultures some of the time. A total of 88.8% of comprehensive ophthalmologists and 76% of cornea specialists initiate treatment with the newer fluoroquinolone antibiotics. A total of 12.1% of comprehensive ophthalmologists and 41% of cornea specialists would select fortified antibiotics for the treatment of corneal ulcers. The percentage of those who feel that fortified antibiotics are superior ranges from 17.7% for comprehensive ophthalmologists to 33.3% for cornea specialists. A total of 65.7% of comprehensive ophthalmologists indicate that the newer fluoroquinolones have impacted their practices, and 58.3% indicate that they represent an improvement over older fluoroquinolones. Conclusions: Most responding ophthalmologists initiate empiric therapy with the newer fluoroquinolone antibiotics for corneal ulcers, forgoing Gram staining and culturing. However, respondents are not universally sanguine about the newer fluoroquinolones. The practice patterns and opinions on antibiotics differ almost universally between comprehensive ophthalmologists and cornea specialists. Larger, more detailed surveys and more specific analyses would help to further establish the factors that lead to differing management choices and opinions.

Retinal Findings in Patients with Alport Syndrome: Expanding the Clinical Spectrum

Aims: To describe previously unreported retinal findings in patients with Alport Syndrome (AS), as well as review the range of ophthalmic manifestations. Methods: Retrospective review of clinical records of patients with AS. Results: Nine patients with AS were identified, of whom three had no eye findings, four showed classic features of AS, and two had new findings, bull’s eye and vitelliform maculopathy. The genetic mutation responsible for the disease in the patient with vitelliform subretinal deposits was identified. Conclusions: Patients with AS can present with a variety of ophthalmic manifestations. Bull’s eye maculopathy and vitelliform deposits can be features of AS. The mechanism of these new macular findings remains unknown. Possible pathophysiological overlap with other maculopathies including age-related macular degeneration is discussed.

In Situ Autofluorescence Visualization of Human Trabecular Meshwork Structure

PURPOSE To characterize the three-dimensional (3-D) structure of the human trabecular meshwork (TM) by two-photon excited (TPEF) autofluorescence (AF) and optical sectioning without conventional histologic embedding and sectioning. METHODS Viable human ex vivo explants of the anterior chamber angle containing the aqueous humor drainage tissue in situ were imaged by TPEF to localize AF and Hoechst 33342 nuclear fluorescence. An autofluorescent marker in Schlemms Canal (SC) aided SC situ visualization. En face and orthogonal views of the TM were generated. RESULTS In the innermost uveal TM, AF signals outlined an intricate 3-D network of fine branching beams with large openings between the beams. In the adjacent corneoscleral TM, beams were thicker and coalesced as plate-like structures with pore-like openings. Linear and coiled AF fibers were visible on the background AF of beams. Deeper, in the external TM, this organization changed to fine fiber arrays orientated in the tissues longitudinal axis, reminiscent of the cribriform plexus of the juxtacanalicular TM (JCT). In the outermost JCT, AF of fine fibers was sparse, then undetectable as optical sections approached the inner wall of SC. Cell nuclei were closely associated with the TM structural extracellular matrix. CONCLUSIONS We have used TPEF and optical sectioning to exploit AF as a useful method to visualize the structure of the human conventional aqueous drainage pathway in situ. Ancillary nuclear staining allowed cell association with the AF structures to be seen. This approach revealed a unique 3-D perspective of the TM that is consistent with known TM structural characteristics.

Surgical outcomes of Baerveldt implants in pediatric glaucoma patients

PURPOSE To evaluate the efficacy of the Baerveldt glaucoma implant (BGI) in children. METHODS The medical records of pediatric glaucoma patients aged 5 months to 19 years who underwent BGI placement by a single surgeon (JCS) between January 1, 2000, and March 1, 2010, were retrospectively reviewed. Patients were evaluated at 3-9 months, 12-18 months, and 24-30 months after surgery. We defined surgical success as a postoperative intraocular pressure (IOP) of >6 mm Hg and <21 mm Hg, without additional glaucoma surgery, loss of light perception, removal of the BGI, chronic hypotony, retinal detachment, malignant glaucoma, endophthalmitis, or phthisis bulbi. Additional outcome measures were tube erosion, corneal decompensation, tube retraction, visual acuity, clinical bleb encapsulation, and choroidal detachment. RESULTS A total of 45 eyes of 36 patients were included. The mean preoperative IOP was 31.6 ± 5.0 mm Hg; the mean postoperative IOP, 16.3 ± 5.1 mm Hg at 3-9 months, 19.5 ± 4.8 mm Hg at 12-18 months, and 18.3 ± 4.8 mm Hg at 24-30 months. Cumulative probability of success was 93.3% at 3-9 months, 86.7% at 12-18 months, and 86.7% at 24-30 months. Overall, 6 eyes failed within 30 months because of uncontrolled IOP (3 eyes), replacement of the glaucoma drainage device (2 eyes), and no light perception (1 eye). CONCLUSIONS In this study cohort, BGI surgery effectively reduced IOP in pediatric patients with refractory glaucoma.

Dual laser-assisted lamellar anterior keratoplasty with top hat graft: a laboratory study.

Objectives: To develop a dual laser-assisted lamellar anterior keratoplasty (LALAK) technique, using excimer and femtosecond lasers to perform surgery on eye bank eyes. Methods: First, we compared corneal stromal surfaces produced by (1) deep excimer ablation, (2) femtosecond lamellar cuts, and (3) manual dissection and evaluated the effect of excimer laser smoothing with fluid masking on each surface. Masked observers graded scanning electron microscopy images on a 5-point roughness scale. Then, we performed a 6-mm diameter excimer laser phototherapeutic keratectomy ablation to a residual bed thickness of 200 &mgr;m, followed by laser smoothing. We used the femtosecond laser to cut donors in a modified top hat design with a thin tapered brim, which fitted into a manually dissected circumferential pocket at the base of the recipient bed. Fourier domain optical coherence tomography was used to measure corneal pachymetry and evaluate graft fit. Results: Deep excimer ablation with smoothing (n = 4) produced a significantly (P < 0.05) smoother surface (grade = 3.5) than deep excimer alone (n = 4, grade = 3.8) or manual dissection with (n = 1, grade = 3.8) and without smoothing (n = 1, grade = 4.8). Deep femtosecond cuts (n = 2) produced macroscopic concentric ridges on the stromal surface. Experimental LALAK was performed on 4 recipients prepared by deep excimer ablation and 4 donors cut with the femtosecond laser. After suturing, good peripheral graft-host match was observed on Fourier domain optical coherence tomography imaging. Conclusion: These preliminary studies show that the LALAK technique permits improved interface smoothness and graft edge matching. Clinical trials are needed to determine whether these improvements can translate to better vision.

Pathological and Immunohistochemical Alterations of the Cornea in Congenital Corneal Opacification Secondary to Primary Congenital Glaucoma and Peters Anomaly.

Purpose: To examine the immunohistochemical alterations in the corneal stroma in Peters anomaly (PA) and congenital glaucoma (CG) compared with age-matched normals and acquired adult corneal scarring (AACS). Methods: The clinical features of PA and CG patients who underwent penetrating keratoplasty were recorded. Immunohistochemistry of cornea and control tissue (normal and acquired corneal scars) was performed with antibodies against collagen types I, III, keratan sulfate, lumican, decorin, and smooth muscle actin followed by semiquantitative analysis of immunolabeling. Results: Clinical features in 2 groups were consistent with PA and CG. Microscopy showed thickened stromal collagen bundles in PA (n = 15), CG (n = 11), and AACS (n = 20) compared with normals (n = 18). PA and CG had distinct immunophenotypes compared with controls. Type I collagen labeling was more intense in CG compared with PA (intensity grading (IG) 2.73 vs. 2.07; P < 0.001). Decorin, lumican, and keratan sulfate labeling was significantly less intense in PA versus AACS (IG; 1.91, 0.38, 1.75 in PA and 2.7, 1.11, 2.61 in AACS. respectively; P = 0.002, P = 0.001 and P = 0.004) and normals (IG 1.92, 1.06, 2.59 respectively; P < 0.001, P < 0.001 and P = 0.005). Collagen I labeling was less intense in CG versus AACS (IG 2.73 vs. 3.09) (P = 0.007). Collagen III labeling was more intense in PA/CG than in normals (IG 0.9, 0.64, 0.62 retrospectively) (P < 0.001 in both). Conclusions: The immunophenotype of the corneal scar in PA and CG differs from normal corneas and so does PA from AACS. The similarities between CG and AACS suggest that CG scarring has an acquired component.