post-PK Eyes Research Articles

High Astigmatism Secondary to Peripheral Ectasia Recurrence in Postpenetrating Keratoplasty Eyes Managed With Miniscleral Contact Lenses.

After penetrating keratoplasty (PK) for keratoconus, vision can be impaired by high-degree astigmatism, particularly in those patients with recurrent peripheral ectasia. Scleral contact lenses (CLs) have long been used in the management of keratoconus both in treatment-naive corneas and those postcorneal transplants. We report the use of miniscleral CLs and their related visual and clinical outcomes in a series of patients with post-PK peripheral rim ectasia. In this retrospective case series, 5 patients (7 eyes) presented because of reduced visual acuity with their spectacles/CLs and/or reduced comfort with their existing rigid gas-permeable lenses. All patients in this series underwent PK more than two decades ago for keratoconus (mean 28.7 years±7.2). All patients demonstrated characteristic thinning at the graft-host junction, with anterior chamber deepening. Central corneas had remained clear in all patients inferring high visual potential. Contact lenses used were No 7 Comfort 15 miniscleral and the Onefit MED scleral with 14.5 mm and 15.6 mm diameters, respectively. All eyes achieved a best-corrected visual acuity of 6/9 or greater. One case had difficulty with insertion and removal and has since discontinued wearing lens at this time. All others are successfully wearing the lenses regularly. Despite advances in CL design, surgical management is still required in some patients. Miniscleral CLs are effective in the refractive management of peripheral ectasia in keratoconic post-PK eyes and should be considered in such eyes before proceeding with repeat surgical intervention.

Characterisation of ectasia after penetrating keratoplasty in keratoconus eyes using anterior segment optical coherence tomography

Background/aimsEctasia of the cornea can occur decades after penetrating keratoplasty (PK), especially in keratoconus eyes. The purpose of this study was to characterise ectasia after PK by morphological findings in...

Correction of high astigmatism with toric intraocular lens in eyes with corneal transplant.

To evaluate the results of toric intraocular lens (IOL) implantation during cataract surgery in eyes with high regular astigmatism associated with prior penetrating keratoplasty (PK). A retrospective data analysis of patients with prior PK, who underwent uncomplicated cataract surgery with hydrophobic toric single piece IOL (EyeCryl Toric®, Biotech Vision Care, Luzern, Switzerland). A total of 18 eyes of 18 patients were included in the study. The mean age was 53.4 ± 12.4 (25-70) years. The mean follow-up period was 15.5 (4-24) months. The mean best corrected visual acuity (BCVA) significantly increased from 1.36 ± 1.0 logMAR to 0.31 ± 0.17 logMAR (p < .001) pre- and post-operative 4 weeks, respectively. There was no significant change in mean BCVA during follow-up; mean BCVA was 0.32 ± 0.17 logMAR at the last visit. The mean pre-operative topographic astigmatism was 6.52 ± 1.80 diopters (D). The mean manifest refraction astigmatism was decreased from 6.55 ± 1.62 D to 2.80 ± 1.43 D (p˂0.001). The mean Surgically induced astigmatism (SIA) was 3.74 ± 0.77 D according to vector analysis. There was no patient with graft rejection or failure, the mean endothelial cell loss rate was 12.75 ± 3.76% (7-17%). There was no patient requiring IOL reposition. Toric IOL implantation during cataract surgery provides an option to correct astigmatism in post-PK eyes with high regular astigmatism. When appropriate patients are selected it is a safe method to achieve significant improvements in visual acuity and astigmatism.

Comparison of long-term outcomes of trabeculectomy and risk factors for failure in eyes post penetrating keratoplasty or Descemet's stripping endothelial keratoplasty.

Purpose:To evaluate the outcomes of trabeculectomy, graft survival, and risk factors for failure in post penetrating keratoplasty (PK) and Descemet’s stripping endothelial keratoplasty (DSEK) eyes.Methods:We reviewed charts of eyes that underwent trabeculectomy for post keratoplasty glaucoma PK [25 eyes] and DSEK [14 eyes] between 1993 and 2019. The demographics, clinical features, and surgical outcomes were evaluated. Success of trabeculectomy was defined as complete when the intraocular pressure (IOP) was >5 and ≤21 mmHg without antiglaucoma medications (AGM) and qualified with AGM. Clear and compact graft was considered for graft success.Results:Median (interquartile range [IQR] preoperative IOP in post-PK eyes and post-DSEK eyes was comparable, 32 (28–38) vs. 31.5 (25–36) mmHg, P = 0.38). Median number of preoperative AGMs was comparable (P = 0.78). Median postoperative follow-up was longer in post-PK, compared with post-DSEK, 2.5 (1.3–3.3) vs. 1 (0.3–2.9) years (P = 0.05). Kaplan–Meier survival estimates for complete and qualified success of trabeculectomy at 3 years were 23.7% and 73.3%, respectively, for PK and 45.8% and 71.6%, respectively, for DSEK. Kaplan–Meier survival estimates for graft survival were 91.8% up to 3 years for PK and 100% until 2 years and 77.8% at 3 years for DSEK. Higher IOP prior to trabeculectomy was a risk factor for failure of trabeculectomy (P = 0.03) and older age was a risk factor for graft failure (P = 0.05) in PK eyes. Number of prior corneal surgeries (P = 0.05) was associated with failure of trabeculectomy and graft failure in post-DSEK eyes.Conclusion:Trabeculectomy had moderate qualified success in post-PK and DSEK eyes at 3 years. Higher pretrabeculectomy IOP and higher number of prior corneal surgeries were significantly associated with failure of trabeculectomy in PK and DSEK eyes, respectively.

Ultrastructural Alterations of Grafted Corneal Buttons: The Anatomic Basis for Stromal Peeling Along a Natural Plane of Separation

To examine the ultrastructure of the natural plane of separation in grafted corneas and evaluate the outcomes of stromal peeling. Interventional case series. In this multicenter study, stromal peeling was attempted in 96 consecutive eyes with unsatisfactory vision following penetrating keratoplasty (PK) for keratoconus (n=79), herpetic keratitis (n=11), and granular dystrophy (n=6). Stromal exchange was performed by (1) 9 mm partial-thickness trephination; (2) creation of a corneal flap across the PK wound; (3) opening of the stromal component of the PK wound until a smooth, translucent natural plane was identified; (4) severing the attachment of the PK scar; (5) stromal peeling along the identified plane; and (6) suturing of donor lamella. Grafted corneas from cases that mandated conversion to PK were processed for transmission electron microscopy. The natural plane of separation was identified in all cases. Stromal exchange was successfully completed in 84 cases (87.5%). Snellen visual acuity ≥20/40 and ≥20/25 was reached in 93% and 72% of cases at 3 years (n=49) and 86% and 62% at 4 years (n=21) postoperatively. Mean endothelial cell loss at 1 year was 6.6% ± 9.5%. Stromal peeling occurred along a plane lined with a continuous layer of keratocytes separating pre-Descemet membrane (DM) stroma, DM, and endothelium from the anterior stroma. Pre-DM stroma was made of poorly organized lamellae containing widely spaced, randomly arranged collagen fibrils. Ultrastructural alterations in the stromal microarchitecture of grafted corneas provide evidence of a natural plane of separation identified intraoperatively. Stromal peeling can be successfully performed in post-PK eyes with various stromal pathology.

Non stripping descemet membrane endothelial keratoplasty in difficult cases: A case series

Endothelial keratoplasty (EK) has been increasingly used instead of penetrating keratoplasty (PK) in the management of post PK graft rejection. Both DSAEK and DMEK involve the surgical removal of the diseased host endothelial cell layer and Descemet's membrane (DM) (descemetorhexis) before transplantation, a technically challenging step, especially in post-PK eyes. Understandably, interest arose when non-stripping DMEK (nDMEK) was described in 2013, and recent studies suggested encouraging results without increased early postoperative failures or complications requiring rebubbling. The purpose of our series was to further study the feasibility and safety of nDMEK and to compare the results with traditional DMEK. This is a single center case series of 3 eyes which underwent nDMEK performed by experienced surgeons (C.P, A.M). Two eyes had nDMEK as a secondary procedure following a failed/rejected PK, while the third case underwent nDMEK on a virgin eye. Undiseased donor DM and a regular host endothelium were required to be eligible for nDMEK. The average change in CCT at last follow-up was -21.2% (±13.3). All required intracameral air injection (rebubbling) within the first few days, with a mean of 2.33 rebubblings per eye, the first one occurring at 6.33±2.52 days after surgery. Non-stripping DMEK surgery appears to be a feasible option, and results are satisfactory at mid to long term. However, in our series, the immediate postoperative period was marked by an increased rebubbling rate. While foreseeable particularly in high-risk cases, surgeons considering this technique should expect a higher risk of early rejection.

Stromal peeling for deep anterior lamellar keratoplasty in post-penetrating keratoplasty eyes

Background/aimsTo evaluate the clinical outcomes of deep anterior lamellar keratoplasty performed by stromal peeling in eyes that have previously undergone penetrating keratoplasty (PK) for keratoconus.MethodsStandardised stromal exchange included (1) 9...

Impact of Forward and Backward Scattering and Corneal Higher-Order Aberrations on Visual Acuity after Penetrating Keratoplasty

ABSTRACTPurpose: To assess the relationship of forward and backward scattering and corneal higher-order aberrations (HOAs) with corrected distance visual acuity (CDVA) after penetrating keratoplasty (PK). Methods: This retrospective study comprised 25 eyes of 25 consecutive patients who underwent PK using the VisuMax femtosecond laser system and age-matched 25 eyes of 25 healthy subjects. We quantitatively assessed objective scattering index (OSI) using the double-pass instrument (OQAS II, Visiometrics), corneal densitometry (CD) and corneal HOAs with the Scheimpflug rotating camera (Pentacam HR, Oculus) 1 year postoperatively. Results: The OSI, CD, and corneal HOAs were significantly larger in the PK group than those in the control group (p ≤ 0.011). We found significant correlations of logMAR CDVA with the OSI (r = 0.477, p = 0.016), and with the anterior, posterior, and total corneal HOAs of the central 4-mm zone (anterior: r = 0.573, p = 0.003, posterior: r = 0.596, p = 0.002, total: r = 0.472, p = 0.017), but no significant association with the CD of the 0–2 mm zone at any layers (anterior: r = 0.236, p = 0.257, center: r = 0.139, p = 0.506, posterior: r = 0.073, p = 0.728, total: r = 0.212, p = 0.308). Similar results were obtained when the analysis was repeated with corneal HOAs of the central 6-mm zone and CDs in 2–6 mm zone. Conclusions: Our pilot study demonstrated that the postoperative CDVA was significantly correlated with OSI and corneal HOAs, but not with backward scattering in post-PK eyes, suggesting that OSI as well as corneal HOAs plays an essential role in postoperative visual performance after PK.

Evaluation of corneal biomechanical properties following penetrating keratoplasty using ocular response analyzer

Purpose:To evaluate corneal biomechanical properties in eyes that has undergone penetrating keratoplasty (PK).Materials and Methods:Retrospective observational study in a tertiary care centre. Data recorded included ocular response analyzer (ORA) values of normal and post-keratoplasty eyes [corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and cornea-compensated intraocular pressure (IOPcc)], corneal topography, and central corneal thickness (CCT). Wilcoxon signed rank test was used to analyze the difference in ORA parameter between post-PK eyes and normal eyes. Correlation between parameters was evaluated with Spearman's rho correlation.Results:The ORA study of 100 eyes of 50 normal subjects and 54 post-keratoplasty eyes of 51 patients showed CH of 8.340 ± 1.85 and 9.923 ± 1.558, CRF of 8.846 ± 2.39 and 9.577 ± 1.631 in post-PK eyes and normal eyes, respectively. CH and CRF did not correlate with post-keratoplasty astigmatism (P =0.311 and 0.276, respectively) while a significant correlation was observed with IOPg (P =0.004) and IOPcc (P < 0.001).Conclusion:Biomechanical profiles were significantly decreased in post-keratoplasty eyes with significant correlation with higher IOP as compared with that in normal eyes.

Comparison of biomechanical parameters in penetrating keratoplasty and normal eyes using the Ocular Response Analyser

To compare corneal hysteresis (CH) and corneal resistance factor (CRF) in eyes 1 year following penetrating keratoplasty (PK) with that of normal eyes using the Ocular Response Analyser. Prospective case comparison of 166 normal right eyes and 34 unilateral post-PK eyes presenting to a teaching hospital in Birmingham, UK. The CH, CRF and Goldmann-correlated intraocular pressure, of each eye was measured using the Ocular Response Analyser. The central corneal thickness (CCT) was measured using an ultrasonic pachymeter. The mean CH was 10.6 ± 2.0 mmHg, standard deviation (SD) and CRF was 10.2 ± 2.0 mmHg (SD) in normal eyes and 8.9 ± 3.3 mmHg and 8.1 ± 3.3 mmHg in post-PK eyes, respectively. The mean CCT was 541.8 ± 36.1 µm in normal eyes and 556.0 ± 69.2 µm in post-PK eyes. The Goldmann-correlated intraocular pressure was 16.1 ± 3.1 mmHg and 12.4 ± 2.9 mmHg in normal eyes and post-PK eyes, respectively. The CCT was found to be higher in post-PK eyes compared with normal eyes but the difference was not statistically significant (P > 0.5). Reduced biomechanical measures were found in post-PK eyes despite a higher mean CCT. This may be due to the altered corneal structure following PK.

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

PurposeTo evaluate corneal biomechanical properties in eyes that had previously undergone penetrating keratoplasty (PK) using the ocular response analyzer (ORA).MethodsWe 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.ResultsThe 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 µm and 556.24±42.84 µm in post-PK and control eyes, respectively (p=0.068).ConclusionsFollowing 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.

Reliability of proton and goldmann applanation tonometers in normal and postkeratoplasty eyes

Objective To compare the reliability of intraocular pressure (IOP) measurements with the ProTon tonometer and the Goldmann applanation tonometer (GAT) in normal and post-penetrating keratoplasty (post-PK) eyes. Design Prospective, nonrandomized, comparative case series. Participants Twenty-four individuals (48 eyes) with no known ocular disorder and 59 patients (59 eyes) that had undergone penetrating keratoplasty (PK) were included in the normal and post-PK groups, respectively. Methods Three readings at 5-minute intervals each were obtained with GAT and ProTon in both the groups. Each reading with ProTon was a mean of five accepted readings with the highest accuracy (standard error of mean, <0.5 mmHg). In post-PK eyes with more than 3.00 diopters of astigmatism or with irregular astigmatism, the mean of two readings taken with GAT in the steepest and flattest axis was considered to be the IOP. Main outcome measures The IOP measurements in all groups were compared using a two-tail paired t test. The coefficient of repeatability and Cronbach’s coefficient α were calculated separately for the IOP measured using both instruments in each group. Results There was no significant difference in the second (r1) and third (r2) IOP reading using the GAT and ProTon tonometers in normal and post-PK eyes. The coefficients of repeatability for GAT and ProTon were 2.64 and 2.49 in normal versus 3.72 and 3.47 in the post-PK group. The Cronbach’s α for GAT and ProTon was 0.94 and 0.95 in the normal group versus 0.95 for both GAT and ProTon in the post-PK group. Conclusions The results of our study show that the ProTon tonometer is reliable and comparable with GAT for recording IOP in normal and post-PK eyes.

Corneal topography for rigid gas permeable lens fitting after penetrating keratoplasty.

Computerized videokeratography may facilitate rigid gas permeable (RGP) contact lens fitting in post-penetrating keratoplasty (post-PK) eyes. We used the EyeSys Corneal Analysis System to create topographic maps of 19 post-PK eyes from October 1990 to April 1991. An initial trial lens was selected based on the average keratometric value from two separate topographic color maps. A standard protocol was used to select the initial trial lens on the basis of computer generated topographic keratometry readings. Final lens selection was based on clinical performance. A comparison of the base curve of the initial contact lens selected using computerized videokeratography and the base curve that would have been selected by standard keratometry showed a statistically significant difference (P = 0.02). Three month follow-up data were also evaluated. There was no statistically significant difference between the base curve of the initially dispensed contact lens and the base curve of the lens worn after 3 months. However, modifications in the fit were made in 9 of 19 patients. Two patients were RGP contact lens failures and were refit with SoftPerm lenses.