Prevalence of Keratoconus Based on Scheimpflug Corneal Tomography Metrics in a Pediatric Population From a Chicago-Based School Age Vision Clinic.

PURPOSE: Determine the pediatric prevalence of keratoconus (KC) using Scheimpflug corneal tomography. METHODS: A prospective observational study was done on subjects aged 3 to 18 years at the Princeton Vision Clinic, Chicago, IL. Scheimpflug tomography (Pentacam HR, OCULUS Optikgerate GmbH) scans (Belin/Ambrósio Enhanced Ectasia BAD3) yielded BAD Final D (Final D) and Back Elevation at the Thinnest Point (BETP) measurements. Criteria differentiating non-KC from KC suspects & KC were, Non-KC -Final D <2.00 in both eyes; KC suspect -Final D ≥2.00 and <3.00 in combination with BETP ≥18 µm for myopia and ≥28 µm for hyperopia/mixed astigmatism in at least one eye; and KC -Final D of ≥3.00 with BETP ≥18 µm for myopia or ≥28 µm for hyperopia/mixed astigmatism in at least one eye. Two thousand two hundred and six subjects were recorded, removing duplicate and poor-quality scans leaving 2007 subjects. RESULTS: Of 2007 subjects, six were classified as KC -prevalence of 1:334, three subjects were KC suspects -prevalence of 1:669, and total prevalence of KC suspects and KC was 1:223. CONCLUSION: The prevalence of KC in children is higher than previously reported, emphasizing the importance of sensitive screening for KC at its earliest manifestation as standard in pediatric comprehensive eye examinations.

Analysis of corneal tomography in select Black and LatinX children.

PURPOSE: Keratoconus (KC) is a bilateral and often asymmetric disease which can progress to corneal thinning and protrusion. Keratoconus in children appears to be more aggressive than in adults. Research on pediatric keratoconus is limited, and treatments rely on research and experience in adult populations. The current study aimed to provide an analysis on the distribution of the corneal tomography measurements in an underserved, Black and LatinX, primarily low-income pediatric population. METHODS: This was a prospective study approved by the Illinois College of Optometry's IRB. A total of 2133 children, presented to a school-based vision clinic within the Chicago Public Schools, were included in the analysis and were classified into three age groups: 3-6 years, 7-12 years, and 13-18 years. Four specific tomography measurements were obtained from the Pentacam (BAD Final D, ART-Max, I-S Ratio, and Thinnest Point Asymmetry). RESULTS: The mean front corneal astigmatism of the study cohort was -1.39D ± 1.45. Tomography indices means were 0.95 ± 0.74 for BAD Final D, 457.34 ± 94.83 for ART-Max, 0.01 ± 0.68 for I-S ratio, and 9.60 ± 25.55 for Thinnest Point Asymmetry. A statistically significant difference was observed among age groups for BAD Final D (p < 0.001), ART-Max (p < 0.001) and Thinnest Point Asymmetry (p = 0.006). CONCLUSION: This study provided the first set of normative data for a pediatric population on the four tomography measurements, offering a reference for potential diagnosis of keratoconus for Black and LatinX children. Further study could include evaluation of additional races along with a comparison with the adult data, which will provide guidance on evaluating the current keratoconus diagnosis criteria to aid early diagnosis of keratoconus in the pediatric population.

Comparative evaluation of refractive surgery candidates with Placido topography, Orbscan II, Pentacam, and wavefront analysis.

PURPOSE: To study the role of the Pentacam (Oculus), Orbscan II (Bausch & Lomb), and WaveScan (Visx) in evaluating topographic features identified as risk factors for ectasia after laser in situ keratomileusis to identify parameters that may be important in interpreting elevation topography and wavefront data when screening refractive surgery candidates. SETTING: Private practice, New York, New York, USA. METHODS: One hundred forty-five eyes of 75 consecutive patients were evaluated for refractive surgery by ultrasound pachymetry (Humphrey Atlas), videokeratography, WaveScan, Orbscan II, and Pentacam. Eyes were classified as normal or suspect based on the Rabinowitz criteria for keratoconus suspect on Placido disk-based videokeratography. Forty-six parameters were evaluated in a comparison of topographically normal eyes and eyes that met the criteria for keratoconus suspect. RESULTS: The suspect group had thinner pachymetry, multiple distinguishing characteristics on the anterior and posterior corneal surfaces by elevation topography, and larger amounts of coma by wavefront analysis. Multivariable regression analysis identified the following as the strongest predictors of a suspect Placido topography: Pentacam, thinner pachymetry and larger differences between the highest and lowest points on the posterior elevation; Orbscan II, higher anterior maximum elevation, horizontal location of the thinnest point on the pachymetry map, and larger differences between the highest and lowest points on the posterior elevation. CONCLUSION: Several parameters provided by the Pentacam, Orbscan II, WaveScan, and pachymetry were statistically correlated with keratoconus suspect, defined by higher asymmetry and steeper curvature on Placido topography.

Transverse keratotomy followed by LASIK for the treatment of naturally occurring astigmatism.

PURPOSE: To evaluate the efficacy of transverse keratotomy followed by LASIK for patients with high amounts of naturally occurring astigmatism. METHODS: Thirteen eyes with naturally occurring astigmatism ranging from -3.75 to -6.50 diopters (D) underwent sequential transverse keratotomy (60 degrees at 6 mm) and LASIK procedures. The effect of these two procedures on the amount of astigmatism was studied. RESULTS: Transverse keratotomy led to a 46% reduction in refractive cylinder from -5.50 +/- 0.80 D to -3.00 +/- 1.00 D. After LASIK, the initial refractive astigmatism was reduced by 90% to -0.50 +/- 0.50 D with a minimum follow-up of 6 months. CONCLUSIONS: The combined technique of transverse keratotomy followed by LASIK is an effective and accurate way to treat high amounts of naturally occurring astigmatism, allowing the size of the optical zone of the excimer laser ablation to be maximized.