Intrastromal Corneal Ring Segment Explantation in Patients With Keratoconus: Causes, Technique, and Outcomes.

PURPOSE: To assess the causes for intrastromal corneal ring segment (Intacs; Addition Technology Inc., Lombard, IL) explantation in patients with keratoconus, and technique for explantation, long-term outcomes, and secondary procedures to correct visual acuity. METHODS: Ten eyes of 8 patients with a history of Intacs explantation between 2004 and 2012 were included in a retrospective study performed at the Bascom Palmer Eye Institute, Miami, Florida. Causes of Intacs removal, surgical technique, preoperative and postoperative corneal examination, and uncorrected and corrected distance visual acuity were documented. Additionally, corneal topography (Tomey, Nagoya, Japan) parameters such as average keratometry and corneal cylinder were assessed. RESULTS: Although the segments were well positioned, the most common cause of Intacs removal was worsening visual acuity (80%). There was no statistically significant difference between pre-Intacs placement, post-Intacs placement, and post-Intacs removal in uncorrected and corrected distance visual acuity, average keratometry, or corneal cylinder, except between 1-year post-Intacs placement corrected distance visual acuity (0.57 logMAR [20/75 Snellen]) and 1-month post-Intacs removal corrected distance visual acuity (0.25 logMAR [20/36 Snellen], P =.03). Four patients underwent penetrating keratoplasty after Intacs removal with good visual outcomes. CONCLUSION: This study demonstrates the visual and structural outcomes that returned to near baseline after Intacs explantation in keratoconic eyes.

The use of Bowman's layer vertical topographic thickness map in the diagnosis of keratoconus.

PURPOSE: To evaluate the use of Bowman's layer (BL) vertical topographic thickness maps in diagnosing keratoconus (KC). DESIGN: Prospective, case control, interventional case series. PARTICIPANTS: A total of 42 eyes: 22 eyes of 15 normal subjects and 20 eyes of 15 patients with KC. INTERVENTION: Bowman's layer 2-dimensional 9-mm vertical topographic thickness maps were created using custom-made ultra high-resolution optical coherence tomography. MAIN OUTCOME MEASURES: Bowman's layer average and minimum thicknesses of the inferior half of the cornea, Bowman's ectasia index (BEI; defined as BL minimum thickness of the inferior half of the cornea divided by BL average thickness of the superior half of the cornea multiplied by 100), BEI-Max (defined as BL minimum thickness of the inferior half of the cornea divided by BL maximum thickness of the superior half of the cornea multiplied by 100), keratometric astigmatism (Ast-K) of patients with KC, and average keratometric (Avg-K) readings. RESULTS: In patients with KC, BL vertical thickness maps disclosed localized relative inferior thinning of the BL. Inferior BL average thickness (normal = 15±2, KC = 12±3 µm), inferior BL minimum thickness (normal = 13±2, KC = 7±3 µm), BEI (normal = 91±7, KC = 48±14), and BEI-Max (normal = 75±8; KC = 40±13) all showed highly significant differences in KC compared with normal subjects (P< 0.001). Receiver operating characteristic (ROC) curve analysis showed excellent predictive accuracy for BEI and BEI-Max with 100% sensitivity and specificity (area under the curve [AUC] of 1) with cutoff values of 80 and 60, respectively. The AUC of inferior BL average thickness and minimum thickness were 0.87 and 0.96 with a sensitivity of 80% and 93%, respectively, and a specificity of 93% and 93%, respectively. Inferior BL average thickness, inferior BL minimum thickness, BEI, and BEI-Max correlated highly to Ast-K (R = -0.72, -0.82, -0.84, and -0.82, respectively; P< 0.001) and to Avg-K (R = -0.62, P< 0.001; R = -0.59, P = 0.001; R = -0.60, P< 0.001; and R = -0.59, P = 0.001, respectively). CONCLUSIONS: Bowman's layer vertical topographic thickness maps of patients with KC disclose characteristic localized relative inferior thinning. Inferior BL average thickness, inferior BL minimum thickness, BEI, and BEI-Max are qualitative and quantitative indices for the diagnosis of KC that accurately correlate with the severity of KC. In our pilot study, BEI and BEI-Max showed excellent accuracy, sensitivity, and specificity in the diagnosis of KC.

Surface quality of human corneal lenticules after SMILE assessed using environmental scanning electron microscopy.

PURPOSE: To assess the cut quality of the anterior and posterior surfaces of intrastromal refractive lenticules removed during small incision lenticule extraction (SMILE). METHODS: The VisuMax femtosecond laser (500 kHz; Carl Zeiss Meditec, Dublin, CA) was used to perform SMILE on 8 eyes of 5 individuals to correct only myopia (no cylinder). The cut energy index was 26 (equivalent to an energy of 130 nJ) with a 2.5 × 2.5 µm spot/track separation. The lenticule diameter was 6.5 mm with a minimum edge thickness of 15 µm and the cap diameter was 7.3 mm with an intended thickness of 120 µm. After laser treatment, the lenticule was loosened with a spatula and removed with forceps. The extracted lenticules were placed in 2% formalin and sent for imaging with an environmental scanning electron microscope. Images of the anterior and posterior surfaces of the lenticules were obtained at multiple magnifications (100×, 250×, and 500×). Surface quality was evaluated by an investigator who specializes in electron microscopy using three criteria: overall surface regularity, percent of surface irregularity, and position of irregular area. RESULTS: Both the anterior and posterior surfaces of the extracted lenticules were smooth and absent of surface irregularities. The cut edges also appeared uniform. Jagged edges were seen in several images, but were clearly caused by the forceps during extraction. CONCLUSIONS: Using the VisuMax laser to perform SMILE produces smooth cuts absent of surface irregularities.

Comparison of IOL power calculation methods and intraoperative wavefront aberrometer in eyes after refractive surgery.

PURPOSE: To compare preoperative methods for calculating intraocular lens (IOL) power versus the intraoperative wavefront aberrometer in eyes with a history of refractive surgery. METHODS: A retrospective study of 46 eyes (33 patients) with previous refractive surgery that underwent subsequent cataract surgery was conducted. Suggested IOL power predicted by ORange intraoperative wavefront aberrometer (WaveTec Vision Systems, Inc., Aliso Viejo, CA) was compared to power predicted by the (1) SRK-T formula using keratometry and axial length measurements from the IOLMaster (Carl Zeiss Meditec, Dublin, CA), (2) average central keratometry (Avg K) from corneal topography, and (3) average IOL power predicted by the American Society of Cataract and Refractive Surgery (ASCRS) web site. No historical information was used for the calculations. IOL power required for emmetropia was back-calculated using manifest refraction and implanted IOL power after cataract surgery. RESULTS: Mean age was 60 ± 7.9 years. Fifteen percent had a history of myopic photorefractive keratectomy (n = 7), 57% myopic LASIK (n = 26), 13% hyperopic LASIK (n = 6), and 22% radial keratectomy (RK) (n = 10). In 37% of cases, ORange predicted IOL power to within ±0.50 diopters (D) of emmetropia, compared to 30% for IOLMaster keratometry, 26% for Avg K, and 17% for ASCRS web site. In eyes after myopic treatment, ORange, IOLMaster, Avg K, and ASCRS web site predicted within ±0.50 D of emmetropia in 39%, 27%, 24%, and 18%, respectively, and within ±1.0 D in 60%, 39%, 39%, and 51%, respectively. In eyes after RK, ORange, Avg K, and ASCRS web site predicted to within ±0.50 D of emmetropia in 14% and the IOLMaster in 43% cases. CONCLUSIONS: Although the ORange most often predicted to within ±0.5 D of emmetropia, no method was able to achieve this accuracy more than 50% of the time. Predictions for eyes after RK were worse than for other types of refractive procedures.

The Quality of Vision questionnaire: subscale interchangeability.

PURPOSE: The purpose of this study is to evaluate the interchangeability of the three subscales of the Quality of Vision (QoV) questionnaire: Frequency, Severity and Bothersome. This will indicate if any of the subscales are predictive of one another and whether respondents need to complete all three subscales. METHODS: Data from four studies were pooled together, totaling 1930 completed questionnaires. Patient groups consisted of spectacle wearers, contact lens wearers, post-laser refractive surgery (including laser in situ keratomileusis, laser-assisted subepithelial keratectomy, and photorefractive keratectomy surgeries for various refractive errors), patients with cataract, and patients having undergone lens implantation surgery (consisting of monofocal, multifocal, and pseudoaccommodative intraocular lenses). The Bland-Altman limits of agreement (LoA) method was used to assess the interchangeability between the three subscales of the QoV questionnaire. RESULTS: The mean difference, standard deviation of the differences, and the LoA for the Frequency versus Severity subscale was 2.8570, 6.784, and -10.4397 to 16.1537, respectively. The mean difference, standard deviation of the differences, and the LoA for the Frequency versus Bothersome subscale was 5.4674, 12.5768, and -19.1831 to 30.1179, respectively. The mean difference, standard deviation of the differences, and the LoA for the Severity versus Bothersome subscale was 2.6104, 9.4444, and -15.9006 to 21.1213, respectively. CONCLUSIONS: The wide LoA found in this study indicate that the three subscales of the QoV questionnaire (Frequency, Severity and Bothersome.) measure different aspects of the latent trait, quality of vision. Users should continue to use all three subscales of the questionnaire to achieve a comprehensive assessment of subjective quality of vision.

Predictability of pseudophakic refraction using patient-customized paraxial eye models.

PURPOSE: To determine whether patient-customized paraxial eye models that do not rely on exact ray tracing and do not consider aberrations can accurately predict pseudophakic refraction. SETTING: Bascom Palmer Eye Institute, Miami, Florida. DESIGN: Prospective study. METHODS: Cataract surgery patients with and without a history of refractive surgery were included. Manifest refraction, corneal biometry, and extended-depth optical coherence tomography (OCT) imaging were performed at least 1 month postoperatively. Corneal and OCT biometry were used to create paraxial eye models. The pseudophakic refraction simulated using the eye model was compared with measured refraction to calculate prediction error. RESULTS: 49 eyes of 33 patients were analyzed, of which 12 eyes from 9 patients had previous refractive surgery. In eyes without a history of refractive surgery, the mean prediction error was 0.08 ± 0.33 diopters (D), ranging from -0.56 to 0.79 D, and the mean absolute error was 0.27 ± 0.21 D. 31 eyes were within ±0.5 D, and 36 eyes were within ±0.75 D. In eyes with previous refractive surgery, the mean prediction error was -0.44 ± 0.58 D, ranging from -1.42 to 0.32 D, and the mean absolute error was 0.56 ± 0.46 D. 7 of 12 eyes were within ±0.5 D, 8 within ±0.75 D, and 10 within ±1 D. All eyes were within ±1.5 D. CONCLUSIONS: Accurate calculation of refraction in postcataract surgery patients can be performed using paraxial optics. Measurement uncertainties in ocular biometry are a primary source of residual prediction error.

Silk Suture Granuloma 37 Years After Scleral Buckle Surgery: A Case Report.

PURPOSE: To present a rare presentation of pyogenic granuloma arising almost 4 decades after a scleral buckle for retinal detachment. METHOD: We describe the clinical presentation, diagnostic workup, and management of a suspicious conjunctival lesion in an immunocompromised patient. We report the histopathological findings and the postoperative outcome. RESULTS: A 58-year-old man with human immunodeficiency virus presented for evaluation of a possible malignant conjunctival lesion in the left eye. The patient reported that the lesion had appeared 1.5 months before presentation with significant growth over the past month. The patient denied any trauma to the eye other than an ocular history of retinal detachment repair with scleral buckle 37 years earlier. Clinical examination revealed a pink, fleshy, mobile, and lobulated conjunctival lesion measuring 7 mm by 10 mm, emanating from the superior-nasal bulbar quadrant. A high-resolution optical coherence tomography revealed highly cellular infiltrate and hyperreflective mass with significant posterior shadowing. Further exploration of the lesion revealed a white, stringy, cauliflower-like material on the underside of the lesion. Surgical excision and pathology subsequently confirmed a diagnosis of pyogenic granuloma with remnants of silk suture. CONCLUSIONS: A diagnosis of pyogenic granuloma secondary to retained silk sutures should be considered in patients with a history of intraocular surgery irrespective of other risk factors and length of time since procedure.

In vivo measurement of the attenuation coefficient of the sclera and ciliary muscle.

We acquired 1325 nm OCT images of the sclera and ciliary muscle of human subjects. The attenuation coefficients of the sclera and ciliary muscle were determined from a curve fit of the average intensity profile of about 100 A-lines in a region of interest after correction for the effect of beam geometry, using a single scattering model. The average scleral attenuation coefficient was 4.13 ± 1.42 mm-1 with an age-related decrease that was near the threshold for statistical significance (p = 0.053). The average ciliary muscle attenuation coefficient was 1.72 ± 0.88 mm-1, but this value may be an underestimation due to contributions from multiple scattering. Overall, the results suggest that inter-individual variations in scleral attenuation contribute to variability in the quality of transscleral OCT images of the ciliary muscle and the outcome of transscleral laser therapies.

Combined anterior segment OCT and wavefront-based autorefractor using a shared beam.

We have combined an anterior segment (AS) optical coherence tomography (OCT) system and a wavefront-based aberrometer with an approach that senses ocular wavefront aberrations using the OCT beam. Temporal interlacing of the OCT and aberrometer channels allows for OCT images and refractive error measurements to be acquired continuously and in real-time. The system measures refractive error with accuracy and precision comparable to that of clinical autorefractors. The proposed approach provides a compact modular design that is suitable for integrating OCT and wavefront-based autorefraction within the optical head of the ophthalmic surgical microscope for guiding cataract surgery or table-top devices for simultaneous autorefraction and ocular biometry.

In vivo measurement of the human crystalline lens equivalent refractive index using extended-depth OCT.

The lens equivalent refractive index (RI) is commonly used in calculations of crystalline lens power. However, accurate determination of the equivalent RI in vivo is challenging due to the need of multiple measurements with different ocular biometry devices. A custom extended-depth Spectral Domain-OCT system was utilized to provide measurements of corneal and lens surface curvatures and all intraocular distances required for determination of the lens equivalent RI. Ocular biometry and refraction were input into a computational model eye from which the equivalent RI was calculated. Results derived from human subjects of a wide age range show a decrease in RI with age and demonstrate the capability of in vivo measurements of the equivalent RI with extended-depth OCT.

Post-Laser In Situ Keratomileusis Epithelial Ingrowth: Treatment, Recurrence, and Long-Term Results.

PURPOSE: To study outcomes after surgical removal of epithelial ingrowth (EI) in post-laser in situ keratomileusis patients, specifically comparing visual results and recurrence rates between 2 different EI management techniques. METHODS: In this retrospective chart review of 67 eyes of 54 patients who underwent surgical treatment for EI after laser in situ keratomileusis between July 1999 and July 2014 at the Bascom Palmer Eye Institute, Miami, FL, surgical techniques, recurrence rates, visual acuity (VA), and refractive error were assessed. RESULTS: Of the 67 eyes, 56 eyes (83.6%) had flap lift + scraping alone, and 11 eyes (16.4%) had flap lift + scraping + suturing. After mean follow-up of 2.5 years, 11 of 56 eyes (19.6%) treated with flap lift + scraping alone had EI recurrence, whereas no eyes treated with flap lift + scraping + suturing had EI recurrence. VA results and refractive errors were better in eyes treated with lift + scraping alone compared with lift + scraping + suturing at 1 month. In the 67 eyes with 1-year follow-up, VA and refractive errors improved from preoperative values and were comparable between groups. CONCLUSIONS: Scraping alone provides significantly better initial visual outcomes but higher EI recurrence rates compared with scrape-suturing. Long-term visual outcomes are comparable between 2 techniques.

Variability of manual ciliary muscle segmentation in optical coherence tomography images.

Optical coherence tomography (OCT) offers new options for imaging the ciliary muscle allowing direct in vivo visualization. However, variation in image quality along the length of the muscle prevents accurate delineation and quantification of the muscle. Quantitative analyses of the muscle are accompanied by variability in segmentation between examiners and between sessions for the same examiner. In processes such as accommodation where changes in muscle thickness may be tens of microns- the equivalent of a small number of image pixels, differences in segmentation can influence the magnitude and potentially the direction of thickness change. A detailed analysis of variability in ciliary muscle thickness measurements was performed to serve as a benchmark for the extent of this variability in studies on the ciliary muscle. Variation between sessions and examiners were found to be insignificant but the magnitude of variation should be considered when interpreting ciliary muscle results.

The Effect of NSAID Pretreatment on Aqueous Humor Prostaglandin E2 Concentration in Eyes Undergoing Femtosecond Laser-Assisted Capsulotomy.

PURPOSE: To assess aqueous humor concentration of prostaglandin E2 (PGE2) after capsulotomy creation using a femtosecond laser (FLAC) in patients pretreated with short-term topical ketorolac versus patients without pretreatment. METHODS: This prospective study comprised consecutive patients scheduled to undergo cataract surgery using a femtosecond laser platform to perform only capsulotomies. An identical protocol for preoperative mydriasis was used for all the eyes included in the study, while aqueous humor was extracted from the anterior chamber of all patients immediately after the initial side port incision. ELISA was performed to quantify aqueous humor PGE2. The patients were divided into 2 groups; in group 1, the patients received short-term topical ketorolac preoperatively, while the patients in group 2 did not receive NSAID pretreatment. RESULTS: Twenty eyes of 20 patients were included in the study (10 eyes in each group). Mean concentration of aqueous humor PGE2 after FLAC was 392.16 ± 162.00 pg/ml and 622.63 ± 331.84 pg/ml for groups 1 and 2, respectively. A statistically significant difference in aqueous humor PGE2 concentration between the two groups (p < 0.05) was demonstrated, with the eyes that received ketorolac pretreatment demonstrating a lower concentration of PGE2. CONCLUSION: Short-term topical use of ketorolac prior to FLAC seems to prevent excessive release of PGE2 in the anterior chamber of the eyes that received NSAID pretreatment when compared to the eyes that did not receive NSAIDs preoperatively.

Effects of Short-term Preoperative Topical Ketorolac on Pupil Diameter in Eyes Undergoing Femtosecond Laser-Assisted Capsulotomy.

PURPOSE: To assess pupil diameter before and after femtosecond laser-assisted capsulotomy in patients who were pretreated with a short-term topical nonsteroidal anti-inflammatory drug (NSAID) (ketorolac) versus those without pretreatment. METHODS: This prospective, randomized, observational case series included consecutive patients scheduled to undergo cataract extraction using the Catalys femtosecond laser platform (Abbott Medical Optics, Inc., Santa Ana, CA) to perform only capsulotomies. The same protocol for preoperative medical mydriasis was used for all patients, whereas pupil diameter was assessed using a surgical ruler immediately before and 3 minutes after femtosecond laser-assisted capsulotomy. The patients were divided into two groups: one received short-term topical ketorolac preoperatively and the other did not receive NSAID pretreatment (control). RESULTS: A total of 42 eyes of 42 patients (1 eye per patient) were included in the study. Mean pupillary miosis was 0.79 ± 1.08 and 1.57 ± 1.19 mm for the ketorolac and control groups, respectively. There was a statistically significant decrease in pupil diameter for both groups individually (P < .05). There was also a statistically significant difference between the two groups (P < .05) with the induced miosis in the eyes that did not receive topical NSAIDs prior to cataract extraction being twofold greater when compared with the miosis of the eyes that received ketorolac pretreatment. CONCLUSIONS: Short-term topical use of ketorolac prior to femtosecond laser-assisted cataract surgery seems to induce significantly less pupillary miosis in comparison to eyes that did not receive NSAID pretreatment. NSAID use is advised prior to femtosecond laser-assisted cataract surgery to minimize pupil miosis-related surgical difficulties or complications during cataract extraction. [J Refract Surg. 2017;33(4):230-234.].

Assessment of eye length changes in accommodation using dynamic extended-depth OCT.

It has been suggested that accommodation induces increases in axial eye length which could contribute to the development of myopia. However, it is debated whether changes in eye length occur during accommodation as the degree of change varies widely across literature. In this study, an extended-depth optical coherence tomography (OCT) system that provides dynamic whole eye biometry was utilized to assess changes in lens thickness (LT) and axial eye length (AEL) in young subjects responding to step disaccommodation stimuli of amplitude 2D, 4D, and 6D. The decrease in lens thickness with disaccommodation was strongly correlated with stimulus amplitude. No statistically significant changes in AEL during accommodation were observed.

Development of a nomogram for femtosecond laser astigmatic keratotomy for astigmatism after keratoplasty.

PURPOSE: To develop a nomogram for femtosecond laser astigmatic keratotomy (AK) to treat post-keratoplasty astigmatism. SETTING: Three academic medical centers. DESIGN: Retrospective interventional case series. METHODS: A review of post-keratoplasty femtosecond laser AK was performed. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, manifest refraction, and keratometry were recorded preoperatively and 1, 3, 6, and 12 months postoperatively. The location, length, depth, and diameter of the AK incisions were recorded, and the surgically induced astigmatic correction was related to these variables using regression analysis. RESULTS: One hundred forty femtosecond laser AK procedures were performed after penetrating keratoplasty (PKP) (n = 129) or deep anterior lamellar keratoplasty (DALK) (n =11), with 89 procedures (80 PKP, 9 DALK) included in the analysis. The mean CDVA improved from 20/59 (0.47 logMAR ± 0.38 [SD]) preoperatively to 20/45 (0.35 ± 0.31 logMAR) postoperatively (P = .013) (n = 46). The mean keratometric astigmatism decreased from 8.26 ± 2.90 diopters (D) preoperatively to 3.62 ± 2.59 D postoperatively (P < .0001) (n = 89). The mean refractive cylinder decreased from 6.77 ± 2.80 D preoperatively to 2.85 ± 2.57 D postoperatively (P < .0001) (n = 69). A nomogram for femtosecond laser AK to treat post-keratoplasty astigmatism was generated using regression analysis. CONCLUSIONS: Femtosecond laser AK significantly improved UDVA and CDVA and significantly reduced keratometric astigmatism and refractive cylinder after keratoplasty. The nomogram generated should improve the accuracy of post-keratoplasty femtosecond laser AK. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any material or method mentioned.

Femtosecond-Assisted Big Bubble: A Feasibility Study.

PURPOSE: To evaluate the feasibility of femtosecond laser-assisted (FA) tunnel creation as a pretreatment for creating a big bubble (BB) to pneumo-dissect the corneal stroma from Descemet membrane. METHODS: Five human cadaver eyes received pretreatment using a femtosecond laser. An intrastromal tunnel, along with a side cut, was achieved using customized femtosecond corneal disruption (custom mask). Before treatment, optical coherence tomography was performed and the intrastromal tunnel was intended to achieve a parallel orientation with respect to the corneal endothelial cell layer (50 µm above the endothelium). Surgical dissection of the side cut using a Sinskey hook was performed, followed by insertion of a deep anterior lamellar keratoplasty cannula into the tunnel and pneumo-dissection (BB). All corneas after treatment were prepared for histologic evaluation (light microscopy). RESULTS: FA pretreatment was successful in all 5 cadaveric corneas, and the BB was achieved in all eyes as well. Histologic evaluation of the corneas revealed complete separation of Descemet membrane and stroma in all eyes, with no remaining stroma attached to Descemet membrane and no signs of perforation. CONCLUSIONS: FABB seems feasible because pneumo-dissection of the corneal stroma from Descemet membrane was achieved in all human cadaver corneas of this experimental study. Optical coherence tomography, corneal histology, and macroscopic evaluation revealed complete Descemet-stromal separation.