The effect of head tilt on keratometric measurement using the IOLMaster.

PURPOSE: To investigate the effect of head tilt on keratometric measurement using the IOLMaster. METHODS: Twenty-seven right eyes of 27 volunteers were examined using a manual keratometer (MK), automated keratometer (AK), and an IOLMaster. MK and AK measurements were performed in the upright head position, whereas IOLMaster measurements were performed in five different head positions (upright, 5° or 15° clockwise head tilt, and 5° or 15° counter-clockwise head tilt). The repeatability of IOLMaster was compared with MK and AK. The keratometric measurements (mean keratometric power, magnitude of astigmatism, and steep meridian) in different head positions were compared. RESULTS: The IOLMaster showed good repeatability of keratometric measurement comparable to MK or AK. 15° and 5° clockwise head tilt resulted in 12.09 ± 9.51 (mean ± SD) (P<0.001 vs upright) and 5.51 ± 5.97 (mean ± SD) degrees (P<0.001) of clockwise rotation of steep meridian, respectively. 15° and 5° counter-clockwise head tilt resulted in 12.49 ± 7.07 (mean ± SD) (P<0.001) and 6.08 ± 5.09 (mean ± SD) degrees (P<0.001) of counter-clockwise rotation of steep meridian, respectively. CONCLUSIONS: The patient's head tilt (5° or 15°, clockwise or counter-clockwise) significantly changed the steep meridian of astigmatism measured using IOLMaster and the steep meridian generally shifted to the direction of head tilt. The importance of maintaining the upright head posture during IOLMaster measurement is demonstrated.

Comparison of de-epithelialized amniotic membrane transplantation and conjunctival autograft after primary pterygium excision.

PURPOSE: To study the efficacy of de-epithelialized amniotic membrane (AM) graft (AmbioDry, Okto Ophtho Inc., Costa Mesa, CA, USA) as an adjunctive therapy after primary pterygium excision in comparison to standard conjunctival autograft. METHODS: A retrospective review of 23 eyes of 22 patients receiving pterygium excision followed by AM transplantation was performed. The results were compared retrospectively with 40 eyes of 36 patients receiving conjunctival autograft after pterygium excision. All patients were Hispanic. Recurrence was defined as regrowth of fibrovascular tissue over the corneoscleral limbus onto clear cornea in the area of previous pterygium excision. RESULTS: The pterygium recurrence rates after AM graft and conjunctival autograft were 35 and 25%, respectively. There was no significant difference in recurrence rate between the two groups (P=0.56). The mean follow-up period was 5.9+/-2.4 months. No major complications were noted in either group. CONCLUSION: This study provides preliminary evidence that de-epithelialized AM graft is as effective as conjunctival autograft in preventing pterygium recurrence in this Southern California Hispanic population.

Topical corticosteroids as adjunctive therapy for bacterial keratitis.

BACKGROUND: Bacterial keratitis is a serious ocular infectious disease that can lead to severe visual disability. Risk factors for bacterial corneal infection include contact lens wear, ocular surface disease, corneal trauma and previous ocular or eyelid surgery. Topical antibiotics constitute the mainstay of treatment in cases of bacterial keratitis where as the use of topical corticosteroids remains controversial. Topical corticosteroids are usually used to control inflammation using the smallest amount of the drug. Their use requires optimal timing, concomitant antibiotics and careful follow up. OBJECTIVES: The objective of the review was to assess the clinical effectiveness and adverse effects of corticosteroids as adjunctive therapy for bacterial keratitis. SEARCH STRATEGY: We searched CENTRAL, MEDLINE, EMBASE, and LILACS up to 15 January 2007. We also searched the Science Citation Index to identify additional studies that had cited the included trial, an online database of ongoing trials (www.clinicaltrials.gov), reference lists of included trials, earlier reviews and the American Academy of Ophthalmology guidelines. We also contacted experts to identify any unpublished and ongoing randomized trials. SELECTION CRITERIA: We included randomized controlled trials evaluating adjunctive therapy with topical corticosteroids in people with bacterial keratitis. DATA COLLECTION AND ANALYSIS: Two review authors independently screened all the retrieved articles. Methodological quality of the one included trial was assessed using forms developed using pre-specified criteria by at least two review authors. We planned to extract data on outcomes using forms developed for the purpose. We planned to report risk ratios for dichotomous outcomes and mean differences for continuous outcomes. MAIN RESULTS: A single trial was eligible for inclusion in the review. Participants in the trial were randomized using a random numbers table. Allocation concealment was not attempted. Masking of participants, and care-providers was also not attempted. Outcome assessment was conducted independently by two physicians. Neither was masked to the treatment allocation. The trial reported the healing rate of epithelial defects and improvement in visual acuity. AUTHORS' CONCLUSIONS: There are no good quality randomized trials evaluating the effects of adjunct use of topical corticosteroids in bacterial keratitis. The only randomized trial we identified in the literature suffered from major methodological inadequacies.

Randomised controlled study of conjunctival autograft versus amniotic membrane graft in pterygium excision.

AIM: To determine whether amniotic membrane can be used as an alternative to conjunctival autograft after pterygium excision. METHODS: 287 eyes with either primary or recurrent pterygium were included in this study. All eyes were randomised to undergo conjunctival autograft or amniotic membrane transplantation after pterygium excision by a single surgeon. 106 eyes in primary pterygium and 14 eyes in the recurrent group were treated with conjunctival autograft, and 148 eyes in primary pterygium and 19 eyes in the recurrent group were treated with amniotic membrane transplantation. Patients were followed up at 6 weeks and 6 months after operation. The main outcome measurement was recurrence rate after surgery. RESULTS: In the conjunctival group, the recurrence rate was 12.3%, 21.4% and 13.1% for primary, recurrent and all pterygia, respectively. In the amniotic membrane group, the recurrence rate was 25.0%, 52.6% and 28.1% for primary, recurrent and all pterygia, respectively. The recurrence rate for all pterygia in the amniotic membrane group was significantly higher than that in the conjunctival group (p = 0.003). CONCLUSIONS: Amniotic membrane graft had a higher recurrence rate than conjunctival autograft. However, it is an alternative choice, especially for advanced cases with bilateral heads or patients who might need glaucoma surgery later.

A new donor cornea harvesting technique for posterior lamellar keratoplasty.

AIMS: To describe a technique for posterior lamellar keratoplasty donor preparation. METHODS: In an experimental study eight human donor research corneas were mounted onto an artificial anterior chamber and deep stromal pockets dissected. Four corneas were mounted in the standard endothelial side down orientation and dissected using standard instruments (group 1). Another four corneas were mounted endothelial side up and dissected using a flat spatula (group 2). Trephined lamellar graft thickness was assessed by ultrasound pachymetry. The grafts were also analysed using vital staining of the endothelium and standard histological preparation. RESULTS: Achieved posterior graft thickness was 118 (SD 32) microm (group 1) and 92 (23) microm (group 2) (p=0.324). Percentage of devitalised endothelial cells was 0.86% (1.48%) (group 1) and 3.9% (2.9%) (group 2) (p=0.185). The dissections using both harvesting techniques remained in plane and were smooth. CONCLUSIONS: A blunt spatula and endothelium side up orientation on an artificial anterior chamber can be used to create posterior lamellar dissections without compromising endothelial cell number or planarity when compared to standard endothelium side down harvest.

A prospective multicenter clinical trial to evaluate the safety and effectiveness of the implantable miniature telescope.

PURPOSE: To evaluate the safety and preliminary efficacy of a novel visual prosthetic device, the Implantable Miniature Telescope, IMT (by Dr Isaac Lipshitz) (IMT), in a phase I trial in patients with significant bilateral central vision impairment from late-stage age-related macular degeneration (AMD). The IMT is designed to reduce the relative size of the scotoma by rendering enlarged (threefold) central visual field images over the central and peripheral retina. DESIGN: Prospective, multicenter, open-label clinical trial. METHODS: In this prospective, multicenter phase I trial, 14 patients aged 60 or older with bilateral geographic atrophy or disciform scar AMD, cataract, and best-corrected visual acuity (BCVA) between 20/80 and 20/400 had an IMT implanted in one eye. Distance and near BCVA, endothelial cell density, and quality of life, measured as activities of daily life (ADL), were evaluated preoperatively and postoperatively. RESULTS: At 12 months, 10 (77%) of 13 patients gained 2 more lines of either distance or near BCVA, and eight (62%) of 13 patients gained 3 or more lines in either distance or near BCVA. Mean endothelial cell density decreased by 13%. All adverse events resolved without sequelae. ADL scores improved in the majority of patients. CONCLUSION: The results of this phase I trial support further evaluation of the IMT in a larger study population with late-stage AMD. A phase II/III trial is in progress.

Re-epithelialization in cornea organ culture after chemical burns and excimer laser treatment.

OBJECTIVE: To describe the epithelial healing rates observed in freshly cultured rabbit corneas chemically burned with high-concentration hydrochloric acid (HCl) and sodium hydroxide (NaOH) and subsequently treated with phototherapeutic keratectomy (PTK). METHODS: We obtained 126 fresh corneoscleral rims from cadaveric New Zealand white rabbits. Each cornea was exposed to 4-mm cellulose sponges soaked in a solution of topical 0.9% isotonic sodium chloride solution, 2M HCl, or 0.5M NaOH. A transepithelial PTK (6-mm zone; 100-microm ablation depth) was then performed using the excimer laser (150-mJ/cm(2) energy pulse; 20 nanosecond duration; and 10-Hz frequency). Corneas were placed in tissue culture, and 1 cornea from each group was taken out of culture each day after treatment. Re-epithelialization was monitored by means of fluorescein staining, slitlamp photography, and histopathological analysis. RESULTS: Corneas treated with HCl and NaOH exhibited immediate epithelial defects that slowly healed over time. In PTK-treated corneas, the re-epithelialization rate was accelerated compared with that of controls (P =.003 for the HCl group, and P<.001 for the NaOH group). The new epithelial layers were smoother in PTK-treated corneas, as confirmed by results of histopathological analysis. CONCLUSION: Corneal damage caused by HCl and NaOH may be modulated in vitro by PTK in this rabbit model. CLINICAL RELEVANCE: After corneal chemical damage, 193-nm excimer laser PTK accelerates epithelial wound healing.

Precision and accuracy of an artificial anterior chamber system in obtaining corneal lenticules for lamellar keratoplasty.

PURPOSE: To determine the precision and accuracy of an artificial anterior chamber and a manual microkeratome in obtaining corneal lenticules for lamellar keratoplasty. SETTING: Department of Ophthalmology, Cornea, External Diseases and Refractive Surgery Service, University of California Irvine, Irvine, California, USA. METHODS: A lamellar keratectomy was performed in 47 human corneoscleral rims. Three lenticule thicknesses (180, 300, and 360 microm heads) and 3 diameters (7.0, 8.0, and 9.0 mm) were attempted. Diameters and thicknesses were measured by planimetry and pachymetry, respectively. RESULTS: Peripheral lenticule thickness was more likely to be within +/-50 microm of the intended depth in thinner cuts (180 microm, 9/15 corneas, 60%; 300 microm, 6/16 corneas, 40%; 360 microm, 3/12 corneas, 33.3%) (P = .045). Eighty percent (32/40 corneas) were within +/-0.5 mm of the expected diameter. Accuracy was best in the 8.0 mm group, with 47.1% (8/17 corneas) within +/-0.2 mm of the expected diameter. A thickness/diameter correlation was not observed (r(s) < or = 0.28). CONCLUSIONS: The precision and accuracy of this system varied according to the attempted thickness and diameter.

Retrocorneal membrane with Descemet's detachment.

PURPOSE: To describe a unique case of retrocorneal membrane with large Descemet's detachment. METHODS: Case report of a 65-year-old man reported intermittent cloudy vision in his left eye. The patient underwent serial ocular examinations and slit-lamp photography over 6 weeks. RESULTS: The patient had an inflammatory-appearing membrane that covered 60% of the posterior cornea, with a subtotal Descemet's detachment. Vision was stable at 20/20, and the cornea remained clear. The patient was empirically treated with topical neomycin/polymyxin/dexamethasone, sodium chloride, and oral acyclovir, and his symptoms improved; however, the retrocorneal membrane persisted. CONCLUSION: This unusual clinical finding may represent reduplicated Descemet's membrane with partial Descemet's detachment secondary to occult deep herpes simplex keratitis. Other possibilities include spontaneous or traumatic Descemet's tear and detachment.

Simple organ cornea culture model for re-epithelialization after in vitro excimer laser ablation.

BACKGROUND AND OBJECTIVE: Most of the in vitro work to characterize the effects of clinical laser surgery on corneal tissues has concentrated on the effects on stromal keratocytes and endothelium with little attention being paid to corneal epithelium. Our purpose is to describe the epithelial healing rates observed in freshly cultured rabbit corneas treated with phototherapeutic keratectomy (PTK). STUDY DESIGN/MATERIALS AND METHODS: Corneas were placed in a simple organ culture system, with media change every 2 days. A clinical excimer laser was used to perform a 6 mm diameter, 100 microm depth transepithelial PTK on 24 cultured rabbit corneas, 1 day after culture initiation. For each post-treatment day, one experimental and one control cornea were removed from culture and stained with fluorescein, photographed, and fixed for histology. Epithelial defect area was measured with digital imaging software and analyzed statistically to assess the re-epithelialization rate. RESULTS: Control corneas, maintained in culture for 1-4 days, had no epithelial defects. Those corneas treated with PTK exhibited an immediate epithelial defect that slowly healed over 3 days. This was confirmed on histopathological analysis. A significant linear trend in re-epithelialization across the time points studied was found (F = 80.48, P = 0.0029). The slope of the linear regression model showed an estimate rate of re-epithelialization of -6.70 over the 3 days. CONCLUSION: We have described the development of a simple, whole organ, rabbit cornea culture model for re-epithelialization after PTK. Our rates of epithelial healing resemble those found in the literature in live rabbit models. Therefore, this model may possibly be used to monitor epithelial wound healing in different corneal diseases or injuries.

Microkeratome-based limbal harvester for limbal stem cell transplantation: preliminary studies.

PURPOSE: To develop a mechanical device to perform limbal transplantation. This procedure is a valuable surgical technique for management of limbal stem cell deficiency. However, the freehand dissection to obtain donor tissue is laborious and time-consuming. METHODS: A manual microkeratome (LSK One; Moria/Microtech, Doylestown, Pennsylvania) using a redesigned head (200 microm thickness, 16-mm blade) was used to create partial thickness corneoscleral caps from human donor globes. RESULTS: Corneoscleral caps obtained from human donor globes included a ring of approximately 1 mm of perilimbal sclera in contiguity to the cornea. Scanning electron microscopy showed a smooth cut surface with some chatter at the margins. CONCLUSION: This instrument ensures an effective and straightforward method to dissect the area where stem cells have been indirectly localized.

Effect of age on the refractive outcome of myopic photorefractive keratectomy.

PURPOSE: To evaluate the effect of age on the outcome of myopic photorefractive keratectomy (PRK). SETTING: University-based refractive surgery practice. METHODS: A retrospective analysis of 197 eyes that had PRK for myopia was performed. Four groups of patients were compared: Group 1, patients < 30 years (n=35); Group 2, patients 31 to 40 years (n=56); Group 3, patients 41 to 50 year s (n=47); Group 4, patients > 50 years (n=59). The percentage of eyes with an uncorrected visual acuity of 20/20 or better and 20/40 or better and the percentage of eyes with spherical correction within +/-0.5 and +/-1.0 diopter (D) of the attempted correction were derived for each age group. The percentage of patients overcorrected and undercorrected by 1.0 D or more in each age group was also calculated. The difference between the percentage of patients who achieved a visual acuity of 20/20 or better in Group 4 and in the younger groups was statistically significant at 3 months (P =.02) but not at 6 months (P =.70) and 12 months (P =.55). The difference between the percentage of patients who achieved an acuity of 20/40 or better was not significant at any time. The difference between the percentage of patients who were within +/-0.5 D of intended correction in Group 4 and in the younger groups was statistically significant at 3 months (P =.001), 6 months (P =.006), and 12 months (P =.008); the difference between the percentage of patients who were within +/-1.0 D of intended correction was not significant at any time. The difference between the percentage of patients overcorrected and undercorrected by 1.0 D or more in Group 4 and in the younger groups was not significant at any time. In the 3 younger groups, age did not significantly affect visual outcome or predictability. However, there was a significant difference between Group 4 and the 3 younger groups in predictability of the refractive outcome at 3, 6, and 12 months. Age may play a role in the outcome of refractive surgery.

Phototherapeutic keratectomy for superficial corneal fibrosis after radial keratotomy.

We report on 4 patients who developed superficial corneal fibrosis after radial keratotomy. All 4 were treated successfully with manual debridement of the epithelium and manual excision of the fibrous scar, followed by phototherapeutic keratectomy.

Corneal sensation after laser in situ keratomileusis.

PURPOSE: To report the time course for the return of corneal sensation following laser in situ keratomileusis (LASIK). SETTING: University-based retractive surgery practice. METHODS: Twenty-eight eyes of 18 patients having LASIK were evaluated. Preoperative and postoperative corneal sensation at the nasal flap hinge, at the central cornea, and within the temporal flap edge were measured before and after LASIK for a 3 week period using the Cochet-Bonnet esthesiometer (Luneau). RESULTS: Corneal sensation initially decreased in all 3 positions of the flap measured after LASIK; the greatest decrease was in the central cornea. Near preoperative corneal sensation returned by 3 weeks. The degree of sensation loss did not appear to correlate with the ablation depth. CONCLUSION: Corneal sensation is significantly decreased for approximately 2 to 3 weeks after LASIK, centrally greater than nasally at the flap hinge or temporally within the flap edge, but it generally returns to near the preoperative level by 3 weeks postoperatively.

Traumatic Acremonium atrogriseum keratitis following laser-assisted in situ keratomileusis.

A 52-year-old man underwent bilateral laser-assisted in situ keratomileusis. Eight months later, he sustained a penetrating corneal injury to the left eye. A dense white infiltrate, unresponsive to antimicrobial therapy, developed in the corneal stroma. Corneal biopsy and eventual penetrating keratoplasty were performed, and both specimens demonstrated fungal elements with branching, septate hyphae. Culture identified the organism as Acremonium atrogriseum. Histopathologic features of this organism and its differentiation from other, more common fungal organisms are discussed herein.

Corneal iron deposits after laser in situ keratomileusis.

PURPOSE: To report the occurrence and features of corneal iron line deposition after laser in situ keratomileusis (LASIK). METHODS: We evaluated 83 eyes undergoing LASIK. Corneal iron line deposition was analyzed with respect to preoperative spherical equivalent, attempted correction, and postoperative time interval. RESULTS: Thirty-five (42.2%) of 83 eyes displayed a distinctive brown-colored corneal iron line of variable density in a ring or patch configuration near the margin of the ablated zone in the overlying corneal flap epithelium. The appearance of this iron line correlated positively with time after surgery (>3 months) and preoperative spherical equivalent (>-4.5 diopters). CONCLUSIONS: Corneal iron line deposition in a ring or patch can be associated with previous LASIK surgery. This iron deposition within the margin of the ablated zone may offer insights into the dynamics of epithelial cell hyperplasia as well as basal cell proliferation, differentiation, and migration after LASIK.

Screening of myopic photorefractive keratectomy in eye bank eyes by computerized videokeratography.

BACKGROUND: In contrast to incisional keratotomy, corneas that have undergone photorefractive keratectomy may be difficult to detect by inspection with slitlamp biomicroscopy alone. Eye bank corneas that have undergone high myopic refractive surgical correction could potentially result in substantial postoperative hyperopic correction if used as donor tissue for corneal transplantation. Surface irregularities or displacement of the treated optical zone within the graft in relation to the entrance pupil of the recipient could result in significant induced astigmatism and distortion. This study examines computerized videokeratographic screening of eye bank globes as a strategy for detecting myopic photorefractive keratectomy. METHODS: Preoperative and postoperative corneal topographic maps of freshly enucleated human and rabbit eyes that have undergone myopic photorefractive keratectomy with an excimer laser were placed in a globe-fixating device and analyzed using a vertically oriented videokeratoscope. The same system was applied in an actual eye bank setting, and potentially transplantable globes from donors without a history of corneal surgery were analyzed. RESULTS: Computerized videokeratography using a vertically mounted system reliably detected photorefractive keratectomy in 12 of 12 human eye bank corneas treated by excimer photorefractive keratectomy in a range between -1.5 to -6.0 diopters. This method also detected similar changes on lased rabbit corneas enucleated 6 weeks after excimer surgery. Data processed with the tangential mode yielded a "bull's-eye" topography pattern reflecting central corneal flattening that was more sensitive in detecting myopic corrections than the conventional axial formula-based color maps. False-positive results were not detected in 96 cadaver globes sequentially screened in the eye bank. CONCLUSIONS: Computerized videokeratography represents a feasible method to screen donor globes for myopic photorefractive keratectomy as shown by the in vitro and rabbit models. However, only whole globes and not corneoscleral sections are amenable to processing with this technique. Tangential maps provided greater sensitivity in detecting low myopic corrections than the axial formula-based color maps.