Biomechanical Properties of the Cornea Using a Dynamic Scheimpflug Analyzer in Healthy Eyes

PURPOSE: To investigate biomechanical properties of the cornea using a dynamic Scheimpflug analyzer according to age. MATERIALS AND METHODS: In this prospective, cross-sectional, observational study, participants underwent ophthalmic investigations including corneal biomechanical properties, keratometric values, intraocular pressure (IOP), and manifest refraction spherical equivalent (MRSE). We determined the relationship of biomechanical parameters and ocular/systemic variables (participant's age, MRSE, IOP, and mean keratometric values) by piecewise regression analysis, association of biomechanical parameters with variables by Spearman's correlation and stepwise multiple regression analyses, and reference intervals (RI) by the bootstrap method. RESULTS: This study included 217 eyes of 118 participants (20–81 years of age). Piecewise regression analysis between Corvis-central corneal thickness (CCT) and participant's age revealed that the optimal cut-off value of age was 45 years. No clear breakpoints were detected between the corneal biomechanical parameters and MRSE, IOP, and mean keratometric values. Corneal velocity, deformation amplitude, radius, maximal concave power, Corvis-CCT, and Corvis-IOP exhibited correlations with IOP, regardless of age (all ages, 20–44 years, and over 44 years). With smaller deformation amplitude and corneal velocity as well as increased Corvis-IOP and Corvis-CCT, IOP became significantly increased. We provided the results of determination of confidence interval from RI data using bootstrap method in three separate age groups (all ages, 20–44 years, and over 44 years). CONCLUSION: We demonstrated multiple corneal biomechanical parameters according to age, and reported that the corneal biomechanical parameters are influenced by IOP.

Effect of Preoperative Crystalline Lens Rise on Vaulting after Implantable Collamer Lens Implantation

PURPOSE: To evaluate the parameters affecting vaulting and correlation between preoperative crystalline lens rise and vaulting after implantable collamer lense (ICL) implantation. METHODS: A total of 53 eyes of 34 patients who underwent ICL implantation were examined retrospectively. White-to-white (WTW) and anterior chamber depth (ACD) were obtained from scanning topography (ORB scan) before surgery. Preoperative crystalline lens rise (CLR) and vaulting at 6 months after ICL implantation were measured using anterior segment optic coherence tomography (AS-OCT). Multiple regression analysis was performed to evaluate the factors affecting central vaulting. RESULTS: The mean preoperative crystalline lens rise was -120 +/- 219 microm, and mean central vaulting 6 months after surgery was 544 +/- 175 microm. Preoperative SE, WTW, ACD, and CLR were significantly correlated with vaulting at 6 months after surgery. With the use of meaningful variables, multiple regression analysis showed that CLR, WTW, ACD and SE, in that order of influence, had significant effects on vaulting and the multiple regression equation was obtained as follows: Vaulting (microm) = (160.913 x ACD (mm)) + (170.134 x WTW (mm)) + (-0.338 x CLR (microm)) + (-23.783 x SE (D)) - 2250.184. CONCLUSIONS: CLR had a stronger influence on vaulting after ICL implantation than the previously proven parameters: WTW, ACD, and SE. In addition to WTW, ACD and SE, CLR should also be considered a new criterion for estimating vaulting after ICL implantation.

A Case of Supratarsal Injection of Triamcinolone in Management of Chronic Thygeson's Superficial Punctate Keratitis

PURPOSE: To report a case of supratarsal injection of triamcinolone for the management of chronic, steroid-dependent Thygeson's superficial punctate keratitis. CASE SUMMARY: A 37-years-old woman complained of redness, photophobia, and tearing in both eyes, which lasted for 6 years. The slit lamp examination revealed multiple intraepithelial and subepithelial, punctated corneal lesions which were elevated and scattered diffusely upon staining with fluorescein dye in both eyes. The patient was diagnosed with Thygeson's superficial punctate keratitis and treated with 0.1% fluorometholone, 0.05% cyclosporin, and 0.15% ganciclovir in both eyes. After 10 months of follow-up, recurrences were reported twice in the right eye, and 7 times in the left eye. The patient was treated with a supratarsal injection of triamcilonone in both eyes and after injection, the patient was treated only with artificial tears. Four months later, the patient did not complain of any symptoms and her cornea was clear. CONCLUSIONS: A supratarsal injection of triamcinolone may be an effective method to prevent recurrence of chronic, steroid-dependent Thygeson's superficial punctate keratitis.

A New Simple Technique for Removal of Subconjunctival Cyst under the Slit Lamp Microscope

PURPOSE: We present a new simple technique to remove subconjunctival cyst under the slit lamp microscope. CASE SUMMARY: A cotton swab was used to verify whether or not the cyst was freely movable under the conjunctiva. After topical anesthesia, we incised the conjunctiva near the cyst using a 30-gauge needle and extracted the cyst through the wound using forceps under the slit lamp microscope. Four cases of subconjunctival cyst were successfully removed with our new technique. During the average five month (2-10 month) follow-up period, there was no recurrence or procedure-related complications. CONCLUSIONS: Some subconjunctival cysts such as an epithelial inclusion cyst which is freely movable without attachment to surrounding tissues can be easily removed with a 30-gauge needle and forceps under the slit lamp microscope. This could be considered as the primary procedure instead of simple aspiration.

Comparison of Wavefront Analysis and Visual Function Between Monofocal and Multifocal Aspheric Intraocular Lenses

PURPOSE: To compare postoperative vision, high-order aberrations, contrast sensitivity, power of accommodation, and depth of focus of monofocal aspheric (TECNIS ZA9003) and multifocal aspheric (TECNIS ZM900) intraocular lenses (IOL). METHODS: Thirty-four eyes which received intraocular lens implantation in the posterior chamber were equally divided into two groups: TECNIS ZA9003 (17 eyes) and TECNIS ZM900 (17 eyes). Before and three months after surgery, visual acuities at near, intermediate, and far distances, and depth of focus were recorded. High order aberrations, spherical aberrations and accommodation power were measured with iTrace, and contrast sensitivity was evaluated using Optec 6500. An independent T-test analysis was used to compare the two groups. RESULTS: There were no significant differences of high order aberrations, spherical aberrations, accommodation power, or distance vision between the two groups at three months postoperatively. The multifocal IOL (TECNIS ZM900) group revealed better intermediate and near vision (p<0.01) and deeper depth of focus, and lower contrast sensitivities (p=0.03) than the monofocal IOL group. CONCLUSIONS: There was no difference in accommodation power between the two groups, but multifocal TECNIS ZM900 IOL exceeds monofocal TECNIS ZA9003 IOL in intermediate and near vision due to diffractive lens design and less spherical aberration by its asphericity.

The Comparison of Central and Mean True-Net Power (Pentacam) in Calculating IOL-Power After Refractive Surgery

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.

A Case of Fungal Keratitis Treated with Voriconazole

PURPOSE: To report drug-resistant fungal keratitis that was treated with voriconazole. CASE SUMMARY: A 31-year-old man was admitted to hospital because of ocular pain, conjunctival injection, and visual weakness 7 days after LASIK surgery. At that time, his vision was counting finger at 30 cm and he presented with corneal epithelial defects, stromal infiltration, and inflammation in the anterior chamber of his eye. He was transferred to our hospital because his infection was resistant to gatifloxacin, tobramycin, amphotericin B, and natamycin eyedrops. At the time of transfer, his vision was counting finger at 30 cm and he presented with corneal epithelial defects, stromal infiltration, and hypopyon. He was treated with topical 2% voriconazole every 2 hours and the lesion improved. However, the hypopyon recurred after 12 days. He was then treated with intracameral voriconazole injection (50 microgram/0.1 cc) and topical 5% voriconazole every hour causing the hypopyon to disappear. His vision improved from counting finger to 20/40 six months after this treatment.

Evaluation of Sensitivity and Specificity of DNA Chip for Diagnosis of Granular Corneal Dystrophy II

PURPOSE: To evaluate the sensitivity and specificity of the DNA chip method in diagnosing patients with granular corneal dystrophy type II (GCD II) induced by mutation of the betaigh3 gene. METHODS: Two hundred twenty-seven patients who visited Severance Eye hospital, corneal dystrophy clinic, from 1 July 2006 to 30 September 2007 were included in this study after history taking and review of their medical records. All subjects were examined by slit lamp microscopy, and blood sampling was done. The sampled blood was used in DNA sequencing and the DNA chip method. RESULTS: Among 227 subjects, 125 (54.6%) patients had GCD II and 103 (45.4%) patients showed normal results according to the DNA sequencing method. The sensitivity and specificity of the DNA chip method were both 100%, while the sensitivity of the slit lamp method was 99.19% and the specificity was 100%. CONCLUSIONS: The DNA chip method for diagnosing GCD II is a more simple, time-saving, and accurate method than DNA sequencing method, and the sensitivity and specificity were both 100%.

The Number of Cases, Cause and Treatment of Avellino Corneal Dystrophy Exacerbated After LASIK

PURPOSE: To present a case report of fungal keratitis related to prolonged overnight use of orthokeratology contact lenses. METHODS: A 13 year-old girl presented with a corneal ulcer in her left eye refractory to antibacterial medication. She had a history of wearing orthokeratology contact lenses overnight for seven months. RESULTS: The organism Aspergillus was isolated by corneal scraping, the contact lens itself, and from the storage case. The patient was treated with topical fluconazole and Natamycin pimaricin in addition to oral itraconazole, resulting in a resolution of the ocular lesion. CONCLUSIONS: The risk of fungal infection as a potential complication of the use of overnight orthkeratology contact lenses should be considered when using these lenses.

Morphological Changes in Extraocular Muscle of Rabbit Eye Produced by Subtenon's Botulinum A Toxin Chemodenervation

PURPOSE: Currently, when injecting botulinum a toxin into the extraocular muscle, EMG (Electromyography) is used for accurate location. In this study, we examined the effects of subtenon botulinum toxin injection without EMG guidance by quantifying the morphological changes of the extraocular muscle fibers in rabbits. METHODS: Using 10 New Zealand white rabbits, 10 units of botulinum a toxin in 0.1 ml of normal saline was injected into the subtenon space of the superior rectus muscles, 5 mm from the muscle insertion in right eyes. As a control, 0.1 ml of normal saline was injected into the subtenon space of the superior rectus muscles in left eyes. At 3 weeks after injections, the bilateral superior rectus muscles of each rabbit were carefully dissected from the globe. Cross-sections of 5 micrometer thickness were obtained at the site, 5 mm from the insertion of each superior rectus muscle. Sections were stained with Masson's trichrome and observed by light microscopy. Using Image-Pro Plus software, the diameter of the orbital layer myofibers was measured and statistical analysis was done using the Kruskal-Wallis test. RESULTS: The average diameter of the orbital layer fiber cells after botulinum toxin injection was 11.5+/-2.26 micrometer at 3 weeks, whereas that of the control was 14.4+/-3.77 micrometer. The difference was statistically significant (p<0.01). CONCLUSIONS: The diameter of myofibers in the orbital layer was reduced after subtenon botulinum a toxin injection. Further studies on the duration of botulium toxin in subtenon space and the change in the size of myofibers depending on the dosage of botulinum toxin will be necessary.

A Case of Inadvertent Anterior Chamber and Corneal Stromal Injection with Antibiotics during Cataract Operation

PURPOSE: To report a case of inadvertent anterior chamber and cornea stromal injection with high dose antibiotics and steroids during cataract operation. METHODS: During cataract operation on a 78 year-old female patient, high dose gentamicin (20 mg/0.5 ml) and dexamethasone (2 mg/0.5 ml) were inadvertently injected into the anterior chamber and cornea stroma when making cornea edema for sealing of the incision sites. Anterior chamber irrigation with balanced salt solution (BSS) was immediately administered. On postoperative day one, extensive cornea edema was noted, and best-corrected visual acuity was 0.2. Descemet's membrane folds were observed around the corneal incision sites. Topical 5% NaCl and 1% prednisolone were started. RESULTS: Four weeks postoperatively, corneal edema began to reduce significantly. At four months postoperatively, corneal edema fully resolved, and best-corrected visual acuity was 0.8. However, some Descemet's membrane folds still remained, and a decrease in the number of endothelial cells was noted by specular microscope. CONCLUSIONS: In this case involving anterior chamber and cornea stromal injection with high dose antibiotics and steroids, immediate anterior chamber irrigation with balanced salt solution seemed an appropriate management, and the patient's long-term visual acuity appears good. To prevent such mistakes, precise labeling of all solutions and use of different syringe needles should be considered.

The Differences in Results of Short Wavelength Automated Perimetry According to Lens Opacities

PURPOSE: Perimetric examination plays an important role in the diagnosis of glaucoma, which is among the leading causes of blindness worldwide. Several examination methods have been developed for early detection of glaucoma. Among those, short-wavelength automated perimetry (SWAP) is the most widely investigated. In this study, the effects of nuclear opacities on SWAP were examined. METHODS: Lens opacities were divided into cortical and nuclear opacity groups ; each group consisted of fifteen eyes. The eyes studied underwent standard white-on-white perimetry and SWAP exams before and after cataract operation. The differences in the results of the examinations were compared between the two opacity groups. The t test was used for comparing the data. RESULTS: In the cortical opacity group, the average difference between the mean deviation before and after the operation was 5.46dB in white-on-white perimetry and 5.02dB in SWAP. In the nuclear opacity group, the average difference between the mean deviation before and after the operation was 4.01dB in white-on-white perimetry and 10.82dB in SWAP. There was no statistically significant difference in the cortical opacity group (p=0.6575). However, there was a statistically significant difference in the nuclear opacity group (p<0.0001). CONCLUSIONS: In clinical situations, more caution should be taken when interpreting the SWAP results of nuclear cataract patients in order to make an accurate decision.