Effects of a Novel Push-through Technique Using the Implantable Collamer Lens Injector System for Graft Delivery during Endothelial Keratoplasty

PURPOSE: To investigate effects of a new push-through insertion method for donor lenticules using an injector system on endothelial viability ex vivo and in a clinical case series of endothelial keratoplasty. METHODS: An ex vivo delivery model was used with porcine corneoscleral rims. We compared the endothelial viability in a new push-through insertion method using the Visian Implantable Collamer Lens (ICL) injector versus that of standard forceps-assisted insertion for lenticule delivery. Twenty porcine corneal lenticules were divided into four groups by insertion method and wound size. Vital dye staining was performed and devitalized areas were semi-quantitatively assessed by digital imaging. In the clinical case series, Descemet's stripping endothelial keratoplasty (DSEK) using the push-through method was performed in seven patients and endothelial outcome was determined six months postoperatively. RESULTS: Mean devitalized areas for the push-through method were significantly lower than for forceps-assisted insertion through 3.2 mm incision (23.99 +/- 2.17% vs. 50.48 +/- 5.07%, p = 0.009) in the ex vivo model. Average endothelial cell counts of donor tissues of patients who underwent DSEK were 26.4% lower six months postoperatively. CONCLUSIONS: Push-through delivery of donor lenticules using the Visian ICL injector system appears to be less harmful to endothelial cells than conventional forceps-assisted delivery.

Effects of a Novel Push-through Technique Using the Implantable Collamer Lens Injector System for Graft Delivery during Endothelial Keratoplasty

PURPOSE: To investigate effects of a new push-through insertion method for donor lenticules using an injector system on endothelial viability ex vivo and in a clinical case series of endothelial keratoplasty. METHODS: An ex vivo delivery model was used with porcine corneoscleral rims. We compared the endothelial viability in a new push-through insertion method using the Visian Implantable Collamer Lens (ICL) injector versus that of standard forceps-assisted insertion for lenticule delivery. Twenty porcine corneal lenticules were divided into four groups by insertion method and wound size. Vital dye staining was performed and devitalized areas were semi-quantitatively assessed by digital imaging. In the clinical case series, Descemet's stripping endothelial keratoplasty (DSEK) using the push-through method was performed in seven patients and endothelial outcome was determined six months postoperatively. RESULTS: Mean devitalized areas for the push-through method were significantly lower than for forceps-assisted insertion through 3.2 mm incision (23.99 +/- 2.17% vs. 50.48 +/- 5.07%, p = 0.009) in the ex vivo model. Average endothelial cell counts of donor tissues of patients who underwent DSEK were 26.4% lower six months postoperatively. CONCLUSIONS: Push-through delivery of donor lenticules using the Visian ICL injector system appears to be less harmful to endothelial cells than conventional forceps-assisted delivery.

A Novel Computerized Visual Acuity Test for Children

PURPOSE: To investigate the efficacy of a computerized visual acuity test, the SNU visual acuity test for children. METHODS: Fifty-six children, ranging from 1 to 5 years of age, were included. In a dark room, children gazed at and followed a circular dot with 50% contrast moving at a fixed velocity of 10 pixels/sec on a computer monitor. Eye movement was captured using a charge coupled device camera and was expressed as coordinates on a graph. Movements of the eye and dot were superimposed on a graph and analyzed. Minimum visualized dot diameters were compared to the Teller visual acuity. RESULTS: Ten eyes (8.9%) of six children failed to perform the Teller visual acuity test, and two eyes (1.8%) of one patient failed to perform the SNU visual acuity test. The observed Teller visual acuity and SNU visual acuity were significantly correlated (p < 0.001). Visual angle degrees converted from the Teller visual acuity and SNU visual acuity were also significantly correlated (p < 0.001). CONCLUSION: The SNU visual acuity using moving targets correlated well with Teller visual acuity and was more applicable than the Teller acuity test. Therefore, the SNU visual acuity test has potential clinical applications for children.

Partial Visual Rehabilitation Using a Toric Implantable Collamer Lens in a Patient with Keratoconus: A Case Report with 20 Months of Follow-up

We report the case of a 37-year-old man with a high myopic keratoconus eye that was treated with a posterior chamber toric implantable collamer lens (ICL) in Korea. The patient had a history of contact lens intolerance and did not want to have a corneal transplantation. His uncorrected visual acuity (UCVA) and best spectacle corrected visual acuity were 0.02 and 0.4 in the left eye, respectively. Preoperatively, the manifest refraction was -12.0 -3.5 x 30A. Postoperatively, the manifest refraction was -1.75 x 180A. UCVA improved markedly after implantation. No intraoperative or postoperative complications were observed during 20 months of follow-up. Toric ICL implantation may be a possible alternative surgical option for the visual rehabilitation of high myopic astigmatism in keratoconus patients with rigid gas permeable contact lens intolerance and in patients who do not want to get a corneal transplant.

Short-Term Outcome of Cataract Surgery Using Torsional-Mode Phacoemulsification for Patients with Low Endothelial Cell Counts

PURPOSE: To evaluate the short-term clinical outcome of cataract surgery using torsional mode phacoemulsification for patients with low endothelial cell density. METHODS: Fifty-seven eyes of 52 patients who underwent torsional phacoemulsification and intraocular lens insertion were included in the present study. Patients were divided into groups according to endothelial cell density (ECD). The control group was comprised of patients with more than 2500/mm2 of ECD and was compared with the low ECD group (LECD) comprised of patients with less than 1600/mm2 of ECD. The LECD group was further divided into a very low ECD group (VLECD) comprised of patients with less than 1000/mm2 of ECD, and a PK-VLECD group comprised of patients with less than 1000/mm2 of ECD after penetrating keratoplasty. Measurement of ECD, cell-size variation coefficient, hexagonality, and central corneal thickness were performed preoperatively and 1 month after surgery. RESULTS: The only one patient who had undergone penetrating keratoplasty with remaining low endothelial density and grade 4 nuclear sclerosis developed overt corneal edema after cataract surgery. No statistically significant differences in the change of endothelial cell characteristics and central corneal thickness before and after surgery were observed between the control and LECD group and between the VLECD and PK-VLECD group. CONCLUSIONS: Even in patients with low ECD, torsional phacoemulsification appears to have a similar effect on the short-term change of endothelial cells, suggesting cataract surgery can be conducted with a staged approach when the density of nucleus is moderate or less dense.

Changes in Clinical Manifestations of Dry Eye Syndrome after Cataract Surgery and the Affecting Factors

PURPOSE: To evaluate the changes in the clinical signs and symptoms of dry eye syndrome before and after cataract surgery according to the main incision location and the type of artificial tears. METHODS: Twenty-four eyes of 17 patients who underwent phacoemulsification and posterior chamber lens insertion from May 2009 to July 2009 were enrolled in the present study prospectively. The main incision location (temporal or superior incision) was determined according to the axis of astigmatism and the postoperative artificial tears (sodium hyaluronate with or without preservatives) were determined randomly. The tear film break-up time (TF-BUT), Schirmer test, esthesiometer, corneal surface grading with Oxford system and ocular surface disease index (OSDI) questionnaire before and 1, 2 and 6 months after surgery were evaluated. The corneal nerve was also analyzed using corneal confocal microscopy (Confoscan 4, Nidek, Italy) before, and 1 and 6 months after surgery. RESULTS: The TF-BUT was significantly longer (p = 0.010) and the OSDI score was significantly lower (p = 0.007) in the patient group with preservative-free sodium hyaluronate than the group with sodium hyaluronate containing preservatives at 6 months after cataract surgery. There were no statistically significant differences according to the main incision location in the sodium hyaluronate without preservatives group. CONCLUSIONS: Symptoms and several signs of dry eye syndrome triggered by cataract surgery decreased with preservative- free artificial tears compared to tears with preservatives.

Intraocular Lens Power Calculation Using IOLMaster and Various Formulas in Short Eyes

PURPOSE: To evaluate the predictability of intraocular lens (IOL) power calculations using the IOLMaster and four different IOL power calculation formulas (Haigis, Hoffer Q, SRK II, and SRK/T) for cataract surgery in eyes with a short axial length (AL). METHODS: The present study was a retrospective comparative analysis which included 25 eyes with an AL shorter than 22.0 mm that underwent uneventful phacoemulsification with IOL implantation from July 2007 to December 2008 at Seoul National University Boramae Hospital. Preoperative AL and keratometric power were measured by the IOLMaster, and power of the implanted IOL was determined using Haigis, Hoffer Q, SRK II, and SRK/T formulas. Postoperative refractive errors two months after surgery were measured using automatic refracto-keratometry (Nidek) and were compared with the predicted postoperative power. The mean absolute error (MAE) was defined as the average of the absolute value of the difference between actual and predicted spherical equivalences of postoperative refractive error. RESULTS: The MAE was smallest with the Haigis formula (0.37 +/- 0.26 diopter [D]), followed by those of SRK/T (0.53 +/- 0.25 D), SRK II (0.56 +/- 0.20 D), and Hoffer Q (0.62 +/- 0.16 D) in 25 eyes with an AL shorter than 22.0 mm. The proportion with an absolute error (AE) of less than 1 D was greatest in the Haigis formula (96%), followed by those in the SRK II (88%), SRK-T (84%), and Hoffer Q (80%). CONCLUSIONS: The MAE was less than 0.7 D and the proportion of AE less than 1 D was more than 80% in all formulas. The IOL power calculation using the Haigis formula showed the best results for postoperative power prediction in short eyes.

Comparison of the Detection Rate, Location and Amount of Retinal Nerve Fiber Layer Defect

PURPOSE: To compare the detection rate of the patients with retinal nerve fiber layer (RNFL) defect and the amount of RNFL defect according to the patients' age. METHODS: Retrospective chart reviews of 22,811 subjects, who visited the health care center from January 2009 to December 2009 were performed. The detection rate, location and average amount of RNFL defect and the proportions of the patients who were diagnosed with glaucoma through Humphrey visual field (HVF) test or determined as a glaucomatous optic disc were compared according to the patients' age. RESULTS: The proportions of the patients whose RNFL defect were detected was highest in the patients 60 years old or older (2.3%) and was statistically significant (p = 0.012). However, there was no significant difference among the other age groups (under 40 years: 1.7%, 40 thru 49 years: 1.5%, 50 thru 59 years: 2.0%). The proportions of the patients who were determined as glaucoma through the HVF test or glaucomatous optic disc were also highest in the patients 60 years old or older (1.4%), however, there was no statistically significant difference (p = 0.070) among the age groups (under 40 years: 1.1%, 40 thru 49 years: 0.9%, 50 thru 59 years: 1.2%). CONCLUSIONS: The RNFL defect is likely to be detected in subjects less than 40 years of age and the detection rate is similar to subjects in their 40's and 50's. The use of fundus photography to detect RNFL defect in a health care center is recommended in subjects under 40 years of age.

Interleukin-17 in Various Ocular Surface Inflammatory Diseases

Recently, the association of Th-17 cells or IL-17 with ocular inflammatory diseases such as uveitis, scleritis and dry eye syndrome was discovered. We assessed whether interleukin (IL)-17 was present in the tears of various ocular surface inflammatory diseases and the tear IL-17 concentrations were clinically correlated with various ocular surface inflammatory diseases. We measured concentrations of IL-17 in tears of normal subjects (n = 28) and patients (n = 141) with meibomian gland dysfunction (MGD), dry eye syndrome (DES), Sjogren syndrome (SS), Stevens-Johnson syndrome (SJS), graft-versus-host disease (GVHD), filamentary keratitis, and autoimmune keratitis associated with rheumatoid arthritis or systemic lupus erythematosus. Clinical epitheliopathy scores were based on the surface area of corneal and conjunctival fluorescein staining. The mean concentrations of IL-17 in tears of patients with filamentary keratitis, GVHD, autoimmune keratitis, SS, DES, MGD, SJS were significantly higher in order than that in normal subjects. Tear IL-17 concentration was significantly correlated with clinical epitheilopathy scores in the patients with systemic inflammatory disease, while tear IL-17 was not correlated with clinical severity of the cornea and conjunctiva in the dry eye patients without any systemic inflammatory disease. Tear IL-17 is likely to correlate clinically with corneal disease severity only in the patients with systemic inflammatory disease.

A Case of Retained Graphite Anterior Chamber Foreign Body Masquerading as Stromal Keratitis

We report a case of a retained graphite anterior chamber foreign body that was masquerading as stromal keratitis. A 28-year-old male visited with complaints of visual disturbance and hyperemia in his right eye for four weeks. On initial examination, he presented with a stromal edema involving the inferior half of the cornea, epithelial microcysts, and moderate chamber inflammation. Suspecting herpetic stromal keratitis, he was treated with anti-viral and anti-inflammatory agents. One month after the initial visit, anterior chamber inflammation was improved and his visual acuity recovered to 20/20, but subtle corneal edema still remained. On tapering the medication, after three months, a foreign body was incidentally identified in the inferior chamber angle and was surgically removed resulting in complete resolution of corneal edema. The removed foreign body was a fragment of graphite and he subsequently disclosed a trauma with mechanical pencil 12 years earlier. This case showed that the presence of an anterior chamber foreign body should always be considered in the differential diagnosis of idiopathic localized corneal edema.

Investigating the Relationship between Serum Interleukin-17 Levels and Systemic Immune-Mediated Disease in Patients with Dry Eye Syndrome

PURPOSE: To investigate the association between dry eye syndrome (DE) and serum levels of interleukin (IL)-17 in patients with systemic immune-mediated diseases. METHODS: IL-17 and IL-23 levels were measured in the sera of patients whose tear production was <5 mm on the Schirmer test. Subjects included patients with chronic graft-versus-host disease (GVHD), rheumatoid arthritis (RA), Sjogren's syndrome (SS), systemic lupus erythematosus (SLE), and no systemic disease. Corneal/conjunctival fluorescein staining was scored and the correlation between the score and the IL-17 level was evaluated. RESULTS: A strong correlation existed between IL-17 level and the type of systemic disease. IL-17 was significantly elevated in patients with chronic GVHD compared to those with RA and SS. IL-17 was not detectable in patients with SLE or in those without systemic disease. IL-23 was not detected in any of the subjects. IL-17 was significantly increased in patients with high fluorescein staining scores. CONCLUSIONS: Our data suggest that IL-17 is involved in the pathogenesis of DE in patients with systemic immune-mediated diseases.

Comparative Analysis of Corneal Refraction and Astigmatism Measured with Autokeratometer, IOL Master, and Topography

PURPOSE: To comparatively analyze the repeatability and consistency between different methods of measuring corneal refraction and astigmatism in order to precisely determine the toric intraocular lens target. METHODS: The medical records of 254 eyes of 192 persons were retrospectively reviewed to compare the repeatability of corneal refraction measured with autokeratometer, IOL Master, and topography. The axis and the amount of the astigmatism were compared between these methods. The differences between the estimated spherical equivalents using measured corneal refractive values and the actual spherical equivalents after cataract surgery were compared to evaluate the expected astigmatic error of each measurement. RESULTS: The average corneal refraction was greater with topography than with IOL Master or autokeratometer. Astigmatism calculated with IOL Master was greater than that measured with topography or autokeratometer. The mean coefficient of variation for mean corneal refraction was 0.19% with autokeratometer, which was smaller than that with IOL Master or topography. In patients with more than 1.5D of astigmatism, there were no significant differences in the axis measured by each instrument. The expected spherical error in IOL calculation was smaller with the measured values from IOL Master and autokeratometer than were those with topography. CONCLUSIONS: The repeatability of measurements for corneal refraction and astigmatism was significantly higher using the autokeratometer and IOL Master, with the highest astigmatic value observed with the IOL master. The axis of astigmatism for each method was consistent in the patients with more than 1.5D of astigmatism.

Analysis of Clinical Characteristics in Phlyctenular Keratoconjunctivitis at a Tertiary Center

PURPOSE: To report the clinical characteristics of patients with phlyctenular keratoconjunctivitis at a tertiary care center in Korea. METHODS: The authors of the present study retrospectively reviewed the medical records of 26 patients who were diagnosed with phlyctenular keratoconjunctivitis, identifying the age and sex at diagnosis, diagnosis of the referring clinic, laterality and location of the lesions, the results of bacterial cultures from the meibum, and treatment options. RESULTS: Eighteen patients (76.2%) were female, and the mean age at diagnosis was 18.4 +/- 10.5 years. Nine patients (34.6%) showed evidence of bilateral diseases, and corneal lesions were observed in 27 eyes of 21 patients. Bacterial cultures from the meibum were performed for 17 patients, with the following results: 6 cases of Staphylococcus epidermidis, 4 cases of Corynebacterium species, and 1 case of Propionibacterium acne. Neovascularization with corneal phlyctenules occurred from the inferior quadrant mostly. Twenty-four patients received the remission treatment of prednisolone acetate 1% eye drops and evidence of regression of new vessels was observed in all patients. Three patients (16.7%) experienced recurrence despite the maintenance treatment of cyclosporine 0.05% eye drops. Visual acuities improved significantly after the remission treatment, as compared to the initial visit. CONCLUSIONS: The phlyctenular keratoconjunctivitis patients who visited the tertiary center in Korea showed similar findings regarding demographics, involvement of blepharitis, and identified microorganisms, as compared with patients in previous reports. However, corneal lesions involving the visual axis were frequent, suggesting that with proper diagnosis and treatment, improvement in visual acuities is possible.

A Case of Endophthalmitis With Necrotizing Scleritis Treated With Vitrectomy and Permanent Amniotic Membrane Transplantation

PURPOSE: To report a case of a patient with infectious endophthalmitis associated with necrotizing scleritis that was treated with pars plana vitrectomy and permanent amniotic membrane transplantation. CASE SUMMARY: A 76-year-old man with pain and visual loss in the right eye was diagnosed with infectious endophthalmitis and necrotizing scleritis. The visual acuity in the right eye was hand motion, and the slit lamp examination showed infection of the conjunctiva and sclera, corneal edema, hypopyon, and necrosis of nasal sclera. An intravitreal antibiotic injection was given, and Pseudomonas aeruginosa was cultured in vitreous fluid. Two days afterward, when vitrectomy was performed, leakage from the scleral microperforation and necrosis of the peripheral cornea was observed. Thus, a 10-layered permanent amniotic membrane transplantation was performed. The patient was given topical antibiotics and steroids, oral prednisolone, and cyclophosphamide postoperatively. After 74 days, endophthalmitis was remitted, and scleritis was well controlled. His visual acuity recovered to 20/40. CONCLUSIONS: Infectious endophthalmitis due to scleral microperforation by necrotizing scleritis can be treated effectively with vitrectomy combined with permanent amniotic membrane transplantation.

Vortex Keratopathy in a Patient Receiving Vandetanib for Non-Small Cell Lung Cancer

We report a case of vortex keratopathy in a patient treated with vandetanib for non-small cell lung cancer (NSCLC). A 44-year-old female who underwent two cycles of chemotherapy for NSCLC complained of visual blurring in both eyes after the initiation of vandetanib, an anti-epidermal growth factor receptor (EGFR) and anti-vascular endothelial growth factor receptor 2 protein tyrosine kinase inhibitor. On ophthalmic examination, visual acuities were 20 / 20 OU and, with the exception of diffuse vortex keratopathy in both eyes, other findings were unremarkable. Vandetanib is believed to have caused vortex keratopathy in this patient. Anti-EGFR properties affecting normal corneal epithelial cell migration and wound healing or drug associated metabolite deposition, which is the case in numerous drug-associated vortex keratopathies, may be possible underlying mechanisms in the formation of this corneal complication.

Effects of Multicurve RGP Contact Lens Use on Topographic Changes in Keratoconus

PURPOSE: To evaluate the effects of wearing rigid gas permeable (RGP) contact lenses on the topographic changes in keratoconus. METHODS: Seventy-seven keratoconic eyes that wore multicurve RGP contact lenses and 30 keratoconic eyes that wore no contact lenses were retrospectively analyzed. The mean follow-ups were 22.6 and 20.5 months in the lens-wearing and control groups, respectively. Visual acuity, comfort, daily wearing time, and corneal staining were evaluated for both groups. The changes in topographic indices were compared between the lens-wearing and control groups. RESULTS: Multicurve RGP lens corrected logarithm of the minimum angle of resolution visual acuity of the lens-wearing group significantly improved from -0.016+/-0.065 to -0.032+/-0.10 at follow-up (p=0.05). In the lens-wearing group with advanced keratoconus, the Sim Kmax, Sim Kmin, apical power, astigmatic index, and anterior elevation significantly decreased from 57.68+/-4.26 diopter (D), 50.50+/-2.32 D, 62.79+/-5.11 D, 7.20+/-0.55 D and 67.36+/-16.30 microm to 55.51+/-4.28 D, 49.62+/-3.26 D, 60.31+/-5.41 D, 5.90+/-0.51 D and 60.61+/-16.09 microm, respectively (paired t-test, p<0.05). The irregularity index of 3 mm did not significantly change. Meanwhile, in the control group, the apical power and irregularity index increased from 55.56+/-7.25 D and 3.06+/-1.68 D to 57.11+/-7.75 D and 3.25+/-1.71 D, respectively (paired t-test, p=0.008, p=0.01). CONCLUSIONS: Properly fitted multicurve RGP contact lenses are not likely to contribute to the progression of keratoconus.

A Case of Alkali Burn Treated With Amniotic Membrane Graft and Forniceal Reconstruction

PURPOSE: To report a case of alkali burn treated successfully with early surgical intervention including amniotic membrane graft and forniceal reconstructionand the restored visual acuity. CASE SUMMARY: A 23-year-old woman was referred for alkali burn of her right eye after being splashed with a drop of 40% sodium hydroxide. Slit-lamp microscopic examination showed the patient's cornea was edematous, and hazy and limbal ischemia involved half of the cornea, which can supposedly lead to eyelid deformity and symblepharon. Debridement of all necrotic tissues, immediate amniotic membrane permanent graft and transient forniceal covering with amniotic membrane were conducted a day after the burn. Corneal and conjunctival epithelial defects were completely healed in five weeks, and visual acuity was restored to 20/20 in eight weeks. Additional surgeries for allogenic limbal transplantation and autologous oral mucosal graft were performed to resolve symblepharon.

Comparison of Optical Performances in Eyes Implanted With Aspheric and Spherical Intraocular Lenses After Cataract Surgery

PURPOSE: To compare optical performances in eyes implanted with aspheric and spherical intraocular lenses (IOLs) after cataract surgery. METHODS: In 88 eyes of 69 patients, spherical (Sensar AR40; Acrysof natural SN60AT) or aspherical (Tecnis ZA9003; Acrysof IQ SN60WF) IOLs were implanted. After one month, contrast sensitivity, depth of focus, and spherical aberration were measured and compared between the groups. RESULTS: Contrast sensitivities of ZA9003 and SN60WF were significantly higher in 12,18 cycles per degree (CPD) under photopic conditions and were also higher in 6,12,18 CPD under mesopic conditions compared to those of respective spherical IOLs. Depths of focus were 1.31 D in ZA9003, 1.67 D in SN60WF, 1.52 D in AR40, and 1.49 in SN60AT, and the differences were not significant. Spherical aberration (Z40) with a 4 mm pupil was -0.032 microm in ZA9003, 0.022 microm in SN60WF, 0.076 microm in AR40, and 0.072 microm in SN60AT. Spherical aberration of SN60WF was significantly lower than spherical IOLs, and that of ZA9003 had the lowest among all IOL groups. Depth of focus significantly correlated with spherical aberration. CONCLUSIONS: Aspheric IOLs were superior in mesopic contrast sensitivity and equal in depth of focus to spherical IOLs. Individual corneal spherical aberration should be considered in the choice of IOLs.

Clinical Manifestation and Predisposing Factors of Infectious Keratitis Following Penetrating Keratoplasty in Korean Patients

PURPOSE: To report the clinical manifestation, predisposing factors, microbiological profiles and treatment outcome of infectious keratitis following penetrating keratoplasty (PK). METHODS: Medical records of the post-PK patients later diagnosed with culture-positive keratitis, between January 2003 and June 2008 at our hospital were retrospectively reviewed. RESULTS: Among 228 eyes of 226 patients who previously had PK, 18 eyes (7.89%) of 16 patients developed microbial keratitis. Fifteen patients had a bacterial infection, of which a Streprococcus species was the most common causative microorganism (6 eyes, 33.3%). Three eyes had fungal infection; one case was co-infected with bacteria. Six eyes (33.3%) presented with a suture-related problem, and sixteen eyes (88.9%) had been using topical glaucoma medications. The suture-related problem and use of glaucoma medication were significantly associated with the development of infectious keratitis (p=0.040 and 0.013, respectively). Remission was achieved in all cases within the mean duration of 2.47 months after treatment initiation. However, visual improvement was not achieved in 11 eyes (68.7%) due to graft opacity. CONCLUSIONS: Early identification of predisposing factors and appropriate management at an early stage may prevent the occurrence of graft infection and improve graft survival.

Evaluation of Corneal Biomechanical Properties Following Penetrating Keratoplasty Using the Ocular Response Analyzer

PURPOSE: To evaluate corneal biomechanical properties in eyes that had previously undergone penetrating keratoplasty (PK) using the ocular response analyzer (ORA). METHODS: We recruited 26 patients who had received unilateral PK. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and cornea-compensated intraocular pressure (IOPcc) were measured with the ORA and were compared to the measurements from the contralateral eyes that did not undergo PK. RESULTS: The CH was 8.95+/-2.59 mmHg in eyes that underwent PK and 9.78+/-1.45 mmHg in the contralateral eyes that did not undergo PK (p=0.077). The CRF was 10.26+/-2.64 mmHg in post-PK eyes and 9.75+/-1.45 mmHg in the contralateral eyes (p=0.509), and the CH-CRF was significantly smaller in post-PK eyes (-1.31+/-2.32 mmHg in post-PK eyes vs. 0.03+/-0.88 mmHg in fellow eyes, p=0.016). The IOPg and IOPcc were significantly higher in the PK group than they were in the control group. The IOPcc's were 20.81+/-7.81 mmHg and 16.27+/-2.49 mmHg in post-PK and control eyes, respectively (p=0.011); and the IOPg's were 19.22+/-7.34 mmHg and 15.07+/-3.03 mmHg in post-PK and control eyes, respectively (p=0.019). The IOPcc-g's were 1.59+/-2.81 mmHg and 1.21+/-1.30 mmHg in post-PK and control eyes, respectively (p=0.412), and the central corneal thickness (CCT)'s were 489.11+/-90.60 microm and 556.24+/-42.84 microm in post-PK and control eyes, respectively (p=0.068). CONCLUSIONS: Following PK, CH tended to decrease while CRF tended to increase, significantly decreasing CH-CRF. A significantly higher intraocular pressure and a thinner CCT following PK may have contributed to the observed changes in these corneal biomechanical parameters.