PURPOSE: To introduce a new convenient and accurate method to measure the angle kappa using ultrasound biomicroscopy (UBM) and corneal topography. METHODS: Data from 42 eyes (13 males and 29 females) were analyzed in this study. The angle kappa was measured using Orbscan II and calculated with UBM and corneal topography. The angle kappa of the dominant eye was compared with measurements by Orbscan II. RESULTS: The mean patient age was 36.4 ± 13.8 years. The average angle kappa measured by Orbscan II was 3.98°± 1.12°, while the average angle kappa calculated with UBM and corneal topography was 3.19°± 1.15°. The difference in angle kappa measured by the two methods was statistically significant (p < 0.001). The two methods showed good reliability (intraclass correlation coefficient, 0.671; p < 0.001). Bland-Altman plots were used to demonstrate the agreement between the two methods. CONCLUSIONS: We designed a new method using UBM and corneal topography to calculate the angle kappa. This method is convenient to use and allows for measurement of the angle kappa without an expensive device.
Corneal Topography* ; Humans ; Male ; Methods ; Microscopy, Acoustic* ; Ultrasonography*

Orbscan-II anterior system was used for early diagnosis of keratoconus. 48 Eyes of 24 patients with suspicious keratoconus were examined by Orbscan-II anterior system from Dec. 1999 to Dec. 2000 and followed up. The values of Diff and anterior chamber depth (ACD) were recorded. Results indicated that values of Diff and ACD were increased in 4 eyes of 2 patients with keratoconus trend during follow-up. Taking advantage of Orbscan-II anterior system to observe the values of Diff and ACD can early diagnose the sub-clinical keratoconus. The values of Diff and ACD can sensitively report the progression of keratoconus.
Anterior Chamber/pathology ; Cornea/pathology ; Corneal Topography/*instrumentation ; Corneal Topography/methods ; Evaluation Studies ; Keratoconus/*diagnosis ; Keratoconus/ultrasonography

Placido disk is widely used in corneal topography. In order to solve the problem that the convex of the corneal can not be precisely located in the Placido corneal topography system, an algorithm of corneal reconstruction based on the Placido disk was introduced. The key of this method is the calculation of radius of corneal convex by using the innermost ring data. Based on image analysis result, we precisely calculated the radius of corneal convex iteratively by connecting the convex and the first ring using a circle, and then calculated the location of all the reflect point and its power. At last we created the pseudo color map of the human corneal. The corneal was simulated by using standard steel sphere, and the calculating errors of the result were all below 0.25D. It showed that the algorithm used in this work could get relatively accurate powers and would have fair stability.
Algorithms ; Cornea ; pathology ; Corneal Topography ; methods ; standards ; Corneal Wavefront Aberration ; Humans ; Image Processing, Computer-Assisted

PURPOSE: To compare the changes in posterior corneal curvature using scanning slit topography (Orbscan II) and Scheimpflug imaging (Pentacam) before and after Epi-laser in situ keratomileusis (LASIK) for myopia. METHODS: In a prospective observational case-series study, 20 myopic patients having undergone Epi-LASIK were examined serially with two different devices, Orbscan II and Pentacam, preoperatively and one month postoperatively. Posterior central elevation (PCE) and posterior maximal elevation (PME) were compared between the two devices, and the changes in parameters after Epi-LASIK were analyzed using a difference map. RESULTS: All parameters (preoperative and postoperative PCE and preoperative and postoperative PME) that were measured using the Orbscan II were significantly greater compared to those of the Pentacam (for all p < 0.001). PCE and PME were significantly increased one month postoperatively in the Orbscan II measurements (p < 0.05) but were not significantly increased in the Pentacam measurements. Also, DeltaPCE and DeltaPME, in the difference map obtained by each serial scanning, were significantly greater in the Orbscan II measurements than with the Pentacam (p = 0.012, p = 0.016). CONCLUSIONS: The Pentacam measurements displayed significantly reduced values in all parameters related to posterior corneal elevation compared to those of the Orbscan II. The Pentacam showed no significant change in posterior corneal curvature after Epi-LASIK, based on the difference map.
Adult ; Corneal Topography/*methods ; Female ; Humans ; Keratomileusis, Laser In Situ/*methods ; Male ; Myopia/*surgery ; Prospective Studies ; Treatment Outcome

PURPOSE: To report two cases of femtosecond laser-assisted small incision deep lamellar endothelial keratoplasty (DLEK) for patients with corneal endothelial decompensation by Fuchs dystrophy and glaucoma METHODS: Femtosecond laser (IntraLase(R); IntraLase Corp., Irvine, CA) with 15 kHz of repetition rate, was used for a 9.5 mm diameter by 400 micrometer thickness donor corneal lamellar dissection. RESULTS: In Case 1, the graft was clear and compact without interface haze, Orbscan showed smooth and regular corneal surface, specular microscopy was unremarkable without sign of corneal endothelial damage, and Optical coherence tomography showed uniform graft well attached to recipient stroma with minimal interface reflection at 2 months postoperation. In Case 2, the graft was clear and compact with minimal interface haze at 1 month postoperation. Femtosecond laser-assisted small incision DLEK was safe and technically feasible in our cases; however, further evaluation is required to determine long-term effects.
Aged ; Aged, 80 and over ; Corneal Edema/*surgery ; Corneal Surgery, Laser/*methods ; Corneal Topography ; Corneal Transplantation/*methods ; Endothelium, Corneal/*transplantation ; Female ; Fuchs' Endothelial Dystrophy/*surgery ; Humans ; Male ; Tomography, Optical Coherence ; Visual Acuity

PURPOSE: To report two cases of femtosecond laser-assisted small incision deep lamellar endothelial keratoplasty (DLEK) for patients with corneal endothelial decompensation by Fuchs dystrophy and glaucoma METHODS: Femtosecond laser (IntraLase(R); IntraLase Corp., Irvine, CA) with 15 kHz of repetition rate, was used for a 9.5 mm diameter by 400 micrometer thickness donor corneal lamellar dissection. RESULTS: In Case 1, the graft was clear and compact without interface haze, Orbscan showed smooth and regular corneal surface, specular microscopy was unremarkable without sign of corneal endothelial damage, and Optical coherence tomography showed uniform graft well attached to recipient stroma with minimal interface reflection at 2 months postoperation. In Case 2, the graft was clear and compact with minimal interface haze at 1 month postoperation. Femtosecond laser-assisted small incision DLEK was safe and technically feasible in our cases; however, further evaluation is required to determine long-term effects.
Aged ; Aged, 80 and over ; Corneal Edema/*surgery ; Corneal Surgery, Laser/*methods ; Corneal Topography ; Corneal Transplantation/*methods ; Endothelium, Corneal/*transplantation ; Female ; Fuchs' Endothelial Dystrophy/*surgery ; Humans ; Male ; Tomography, Optical Coherence ; Visual Acuity

OBJECTIVE: To explore the postmortem changes of cornea thickness measured by ultrasonic pachymetry. METHODS: Eleven rabbits were randomly divided into two groups: one group with intact corneal epithelium and another group without intact corneal epithelium. In the later group, the corneal epithelium of the rabbit was scraped using mechanical elimination method. The corneal thickness was monitored continuously by ultrasonic pachymetry at several postmortem interval points in rabbits of the two groups. The changes of corneal thickness and postmortem interval were explored by relative regression analysis. RESULTS: The thickness of the cornea showed a strong non-linear correlation with the postmortem interval in the group with intact corneal epithelium. The group with intact corneal epithelium showed the correlation coefficient 0.922 and the group without intact corneal epithelium showed the correlation coefficient 0.822, respectively. CONCLUSION The corneal thickness measured by ultrasonic pachymetry shows a potential value for estimating early postmortem interval. The intact corneal epithelium is a crucial factor for the measurement of cornea thickness by ultrasonic pachymetry.
Animals ; Cornea/pathology* ; Corneal Topography/methods* ; Epithelium, Corneal/ultrastructure* ; Female ; Forensic Pathology/methods* ; Male ; Postmortem Changes ; Rabbits ; Regression Analysis ; Reproducibility of Results ; Time Factors ; Ultrasonography

PURPOSE: To evaluate reliability of Fourier-domain optical coherence tomography (OCT) (RTVue), time-domain OCT (Visante), and slit-lamp adapted ultrasonic pachymetry (SL-US) in the measurement of central corneal thickness (CCT). MATERIALS AND METHODS: Thirty healthy volunteers visited our clinic 3 times and fifty eyes were measured by one physician. RTVue and Visante were randomly performed, and then SL-US, in which the ultrasound probe was inserted into the Goldmann tonometry mount, was done. During the second visit, each measurement was repeated 3 times. Measurements on the second visit were averaged, and agreement among the instruments was investigated with Bland-Altman plots. RESULTS: RTVue showed smaller repeatability coefficient than Visante and SL-US (4.7, 8.3, and 7.7 microm, respectively). Intersession reproducibility of RTVue and Visante was worse than their repeatability. CCT of RTVue was estimated to be maximally different by 11.8 microm from CCT of Visante and 8.8 microm from CCT of SL-US. The repeatability coefficient of SL-US was 7.7 microm and its reproducibility was similar to the repeatability. CONCLUSION: CCT measured by RTVue showed good reliability and generally agreed with Visante and SL-US. SL-US was as reliable as triple touching conventional US even with a single touch on the cornea.
Adult ; Cornea/*anatomy & histology/pathology/ultrasonography ; Corneal Topography ; Female ; Humans ; Male ; Reproducibility of Results ; Tomography, Optical Coherence/*methods

PURPOSE: To compare the accuracy of central true net corneal power (cTNP) and mean true net corneal power (mTNP) of the Pentacam system to give a keratometry (K) reading for calculating IOL (intraocular lens) power in eyes following refractive surgery. METHODS: Refraction, an automated K-reading (Km), cTNP and mTNP were measured for 15 eyes that required cataract surgery and had previously undergone refractive surgery. The difference between postoperative manifest refraction values and target refraction values calculated with the SRK/T formula using cTNP were compared with the one using mTNP. RESULTS: The mean deviation from the desired post-cataract refractive outcome was 0.60 diopter (D) +/-0.47 (standard deviation) using cTNP; 0.75+/-0.54 using mTNP (p=0.386). The actual refraction was within +/-0.50D of the intended refraction for 60% (cTNP) and 33.3% (mTNP) of eyes, and within +/-1.00D for 93% (cTNP) and 66.7% (mTNP) of eyes. CONCLUSIONS: Although not statistically significant, the cTNP showed better accuracy than mTNP to give a keratometry (K) reading for post-refractive surgery eyes requiring cataract surgery.
Adult ; Cornea/*pathology/physiopathology/surgery ; Corneal Topography/*methods ; Female ; Humans ; *Lenses, Intraocular ; Male ; Middle Aged ; Myopia/*surgery ; Prosthesis Design ; *Refraction, Ocular ; *Refractive Surgical Procedures

PURPOSE: To compare the effects of performing a single limbal relaxing incision (LRI) combined with a clear corneal incision on a corneal astigmatism with that of paired LRIs in cataract surgery. METHODS: Medical records for 25 eyes in 20 patients who had undergone LRIs during cataract operations for with-the-rule astigmatism of 1.5 diopters (D) or more in topography were retrospectively reviewed. Single or paired LRIs were assigned randomly and were performed on the steepest axis; the degrees of arc were determined using the modified Gills nomogram. A clear corneal wound was made on the steepest vertical axis. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, and corneal astigmatism on topography were evaluated preoperatively and one month postoperatively. Naeser's polar value analysis was used to assess the efficacy of the LRIs. RESULTS: The mean depth of the LRIs and degrees of arc were 620+/-31 micrometer (87.1% of corneal thickness) and 56.84+/-19.68degrees, respectively. The mean postoperative UCVA and BCVA (log MAR) were significantly improved (0.51+/-0.37 and 0.09+/-0.12, respectively) (p<0.05). Average refractive and corneal astigmatisms were significantly reduced by 49.4 percent and 32.4 percent, respectively (p<0.05). The single LRI combined with clear corneal incision showed reduced efficacy in refractive astigmatism by 47 percent, which is similar to that of paired LRIs where a 48 percent reduction in efficacy was seen. CONCLUSIONS: The short-term effects of a single LRI combined with clear corneal incision on a corneal astigmatism appears to be as effective as performing paired LRIs when combined with cataract incision.
Aged ; Astigmatism/*surgery ; Cornea/*surgery ; Corneal Topography ; Female ; Humans ; Male ; Refractive Surgical Procedures/*methods ; Retrospective Studies ; Statistics, Nonparametric ; Treatment Outcome ; Visual Acuity