Sutureless femtosecond anterior lamellar keratoplasty: A 1-year follow-up study

Aim:

To study the safety and efficacy of sutureless femtosecond anterior lamellar keratoplasty (FALK) in patients with corneal stromal opacities.

Materials and Methods:

Eleven eyes of 11 consecutive patients with corneal stromal opacities involving < 250 μ due to various pathologies were included in the study. Preoperatively, all underwent anterior segment imaging with spectral domain optical coherence tomography (SD-OCT) (Bioptigen Inc., Durham, North Carolina, USA) to measure the depth of the stromal opacity. All patients underwent FALK, and bandage contact lens was placed for a period of 2 weeks. Postoperatively, uncorrected visual acuity, best corrected visual acuity (BCVA), and SD-OCT evaluation were performed.

Results:

All patients showed significant improvement in BCVA. The mean postoperative BCVA (in decimals) improved from 0.11 ± 0.06 preoperatively to 0.59 ± 0.08. There were no intraoperative or significant postoperative complications that were noticed.

Conclusion:

FALK is a safe and effective alternative to deep anterior lamellar keratoplasty or penetrating keratoplasty in the treatment of anterior stromal opacities.     

Late onset corneal ectasia after LASIK surgery

Purpose

To report late onset corneal ectasia following myopic LASIK.

Methods

A retrospective cohort case series. Nineteen patients with late onset corneal ectasia following LASIK procedure were examined at The Eye Center, Riyadh, Saudi Arabia. Patients underwent LASIK for myopia with spherical equivalent ranging from −1.4 to −13.75 diopters. Age and gender, history of systemic or local diseases, and time of onset of corneal ectasia were recorded. Eye examination and corneal topographical analyses were done before and after LASIK surgery.

Results

Nineteen patients (29 eyes) with late onset corneal ectasia were identified from 1998 to 2008 in 13 male and six female patients. The mean follow-up period was 108 ± 23 months (range 72–144 months). No patient had pre-operative identifiable risk factors for corneal ectasia and the mean time of onset was 57 ± 24 months (range 24–120 months after LASIK). The pre-operative values included mean central pachymetry 553 ± 25 μm, mean keratometry reading of 42.9 ± 1.5 diopters, average oblique cylinder of 1.4 ± 1.2 diopters, posterior surface elevation of 26 ± 2.1 diopters, corneal flap thickness of 160 μm, mean spherical equivalent of −5.6 ± 3.6 diopters, and calculated residual corneal stromal bed thickness was 288 ± 35 μm. Three (5 eyes) patients developed ectasia after pregnancy. Three (4 eyes) patients developed corneal ectasia following severe adenoviral keratoconjunctivitis and had positive PCR for adenovirus type 8.

Conclusions

Corneal ectasia may develop many years after LASIK surgery and symptoms could go undetected for some time. Pregnancy and adenoviral keratoconjunctivitis occurred post-operatively in six patients.     

Outcomes with the Boston Type 1 Keratoprosthesis at Instituto de Microcirugía Ocular IMO

Purpose

To report the outcomes on the Boston Type 1 Keratoprosthesis at our institution.

Design

Retrospective analysis case series.

Participants

We analyzed 54 eyes of 53 patients who previously underwent Boston Type 1 Keratoprosthesis surgery at our institution from July 2006 to March 2011.

Methods

Preoperative and postoperative parameters were collected and analyzed.

Main outcome measures

Visual acuity and keratoprosthesis stability.

Results

Common preoperative diagnoses were penetrating keratoplasty failure in 49 eyes (90.7%), chronic keratitis in 2 eyes (3.7%), ocular cicatricial pemphigoid in 1 eye (1.85%), Stevens Johnson syndrome in 1 eye (1.85%) and corneal vascularization in 1 eye (1.85%). Additionally, 40 eyes (74%) had preoperative glaucoma, and an Ahmed valve was implanted in 55% of them. Preoperative BCVA ranged from 20/200 to light perception. At an average follow-up of 20.15 months ± 12.7 (range, 1–56), postoperative vision improved to ⩾20/200 in 18 eyes (33.3%) and ⩾20/50 in 4 eyes (7.4%). The graft retention was 96%.

Conclusions

The Boston Type 1 keratoprosthesis is a valid option for high-risk patients. The design improvements in the Boston keratoprosthesis, as well as the daily implementation of the therapeutic methods, have notably diminished occurrence of the most serious complications, such as corneal necrosis and endophthalmitis. As such, glaucoma and its subsequent complications now stand as the most prevalent prognostic factor in the long term.     

Femtosecond laser-assisted deep anterior lamellar keratoplasty for keratoconus and keratectasia

AIM: To describe the initial outcomes and safety of femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK) for keratoconus and post-LASIKkeratectasia.METHODS:In this non-comparative case series, 10 eyes of 9 patients underwent DALK procedures with a femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany). Of the 9 patients, 7 had keratoconus and 2 had post-LASIK keratectasia. A 500 kHz VisuMax femtosecond laser was used to perform corneal cuts on both donor and recipient corneas.The outcome measures were the uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), corneal thickness, astigmatism, endothelial density count (EDC), and corneal power.RESULTS: All eyes were successfully treated. Early postoperative evaluation showed a clear graft in all cases. Intraoperative complications included one case of a small Descemet’s membrane perforation. Postoperatively, there was one case of stromal rejection, one of loosened sutures, and one of wound dehiscence. A normal corneal pattern topography and transparency were restored, UCVA and BCVA improved significantly, and astigmatism improved slightly. There was no statistically significant decrease in EDC.CONCLUSION: Our early results indicate that femtosecond laser-assisted deep anterior lamellar keratoplasty could improve UCVA and BCVA in patients with anterior corneal pathology. This approach shows promise as a safe and effective surgical choice in the treatment of keratoconus and post-LASIK keratectasia.     

Deep anterior lamellar keratoplasty with a manual spatula: Anatomical and functional results

Objective:

Evaluate the anatomical, refractive, and functional results of an innovative technique of deep anterior lamellar keratoplasty with a manual spatula.

Materials and Methods:

We evaluated the results and examinations of 16 eyes from 14 patients who underwent deep anterior lamellar keratoplasty using the technique described by Ferrara. Residual bed thickness after keratoplasty was evaluated postoperatively using Visante. The measurement was performed using a technique similar to that used to measure flap thickness after laser in situ keratomileusis refractive surgery. The measurements were performed at the center of the cornea in an area comprising the central 3-mm in the 45° and 135° meridians.

Results:

Best-corrected visual acuity was 0.34 ± 0.18 LogMar (0.09 to 0.60 LogMar), the spherical equivalent was -4.31 ± 3.38 D (+0.25 to -9.50 diopters), and keratometry was 45.75 ± 2.77 D (41.11 to 52.48 diopters) postoperatively. Corneal astigmatism was 3.19 ± 2.78 D (0.18 to 11.81 diopters). Residual stromal bed thickness measured by optical coherence tomography showed values of 67.1 ± 24.3 μm (30 to 109 μm). The statistical correlation by Spearman''s test between the best-corrected visual acuity and the residual stromal bed thickness was 0.11 (P = 0.67).

Conclusion:

Deep anterior lamellar keratoplasty, in which manual dissection was performed using an instrument similar to that used to implant corneal rings, provided good visual and anatomical results.     

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.     

Long-term outcomes of penetrating keratoplasty in keratoconus:analysis of the factors associated with final visual acuities

AIM: To investigate the long-term results of penetrating keratoplasty (PK) in patients with keratoconus (KC) and to evaluate factors that might influence the final visual outcome.METHODS:We retrospectively reviewed the data of all patients with clinical KC who had undergone PK by a single corneal surgeon in a single center from May 1980 to December 2005. The age of the patients, preoperative best-corrected visual acuity (BCVA), corneal thickness, death to preservation time, and preservation to transplantation time were recorded. Additionally, postoperative complications such as graft rejection, development of glaucoma and specular microscopy were checked during the follow-up.RESULTS:Sixty-nine eyes from 69 patients were finally included. The follow-up period was 8.64±6.13y. Graft rejection occurred in 4 eyes of 69 cases (5.8%), and the time to graft rejection was 2.1±1.3y. A Kaplan–Meier survival analysis showed that the estimated cumulative probability of graft rejection at 6, 13, and 17y after PK were 95.6%, 90.0%, and 78.8%, respectively. When we evaluated factors that might influence final BCVA in eyes, no disparity donor-host trephine size (same graft size) as well as higher spherical equivalent, and average K-value were associated with higher final BCVA. (P=0.006, 0.051, 0.092, and 0.021 in eyes with follow-up <8y; P=0.068, 0.065, and 0.030 in eyes with follow-up ≥8y, respectively).CONCLUSION: The long-term results of PK in patients with KC were favorable with a high percentage of good BCVA. Less myopic change and low average K-reading, as well as a surgical technique using the same size donor-recipient button may provide better visual outcomes particularly in patients with KC.     

Ocular surface rehabilitation: Application of human amniotic membrane in high-risk penetrating keratoplasties

Background

Human amniotic membrane is a versatile tool for management of ocular surface disorders. This study evaluates the effect of cryopreserved human amniotic membrane (hAM) on one-year survival of penetrating keratoplasties (PKP) in high-risk recipients.

Method

This is a retrospective noncomparative cohort study of 58 consecutive eyes undergoing PKP with concurrent placement of a self-retained cryopreserved hAM (PROKERA®) at a tertiary care center from January 2009 to July 2010.

Results

Mean patient age was 66.7 ± 17.2 years and 30 (54%) were males. 51 eyes were pseudophakic and one aphakic. 27 eyes were glaucomatous; 24 had glaucoma drainage device and 2 had previous endocyclophotocoagulation. 12 patients had PKP for the first time and 46 had repeat PKP (average number of prior PKP = 1.63 ± 1.1, range: 1–5).Risk factors for graft failure included repeat PKP (79.3%), corneal neovascularization (51.7%), preexisting glaucoma (46.6%), and presence of anterior synechiae (37.9%). Both First Transplant and Repeat Transplant groups had similar survival rates until 6 months after transplant (75% vs 74%, odds ratio = 1.06, p = 1.00). At 12 months, First Transplant group showed a better survival rate (67% vs 43%, odds ratio = 2.60, p = 0.20). Eyes with >3 risk factors had a higher graft failure rate (odds ratio = 5.81, p = 0.003).

Conclusion

Survey of the literature suggests that high-risk PKP with concurrent hAM placement demonstrate comparable graft survival. Presence of multiple risk factors is associated with poor survival.     

Corneal spherical aberration and its impact on choosing an intraocular lens for cataract surgery

Purpose

To analyze the post operative results of targeting zero spherical aberration by selecting the best-fit aspheric intraocular lens (IOL), based on preoperative corneal spherical aberration of patients with phacoemulsification surgery.

Setting

AlHokama Eye Specialist Center, Riyadh, Saudi Arabia.

Period

From the 1st of October 2012 until the 10th of April 2013.

Methods

Fifty-three eyes, were subjected to phacoemulsification cataract surgery and divided into two groups, 34 eyes were implanted with aspheric IOLs based on their corneal spherical aberration targeting post operative zero total spherical aberration, whereas 19 eyes were implanted with neutral aspheric IOLs regardless of their corneal spherical aberrations (CSAs). As a pre and post routine examination, patients underwent: slit lamp testing, intraocular pressure (IOP) measuring, fundus examination, best spectacle corrected visual acuity (BSCVA), manifest refraction, pupillometry, axial length, contrast sensitivity, and corneal aberration measurement using Pentacam HR (OCULUS, Germany) at the 6-mm optical zone. Post operatively, visual function questionnaire (VF-14) was asked to all patients.

Results

Fifty-three eyes of 45 patients, whose age ranged from 45 to 90 years old, were available for analysis, the selected group was implanted with: Tecnis ZA9003 or ZCB00 (Abbott Medical Optics) IOLs in 17 eyes with corneal spherical aberration of more than 0.27 μm, AcrySof IQ SN60WF (Alcon Laboratories Inc.) IOLs were implanted in 4 eyes with CSA = (0.2–0.27) μm, and Rayner 970C, 920H or 620H IOLs with spherical aberration (SA) = 0 in 13 eyes with CSA less than 0.20 μm. The other group of 19 eyes was implanted with aspheric IOLs that have zero spherical aberration (Rayner 970C or 920H) regardless of their CSA. Root mean square (RMS) of total corneal aberration positively correlates to the pupil diameter (P = 0.0031, r = 0.3989). A low negative correlation was found between the corneal spherical aberration of the fourth ordered (Z40) and the axial length (r = −0.2009, P = 0.1492). There was no significant difference between the selected and non-selected group in contrast sensitivity, best spectacle corrected visual acuity, and visual satisfaction (P = 0.5316, P = 0.3919, P = 0.7667).

Conclusion

Customized selection of aspheric IOLs based on the eyes’ corneal spherical aberration has no significant importance comparing their results with the non-selected group.     

A Comparison of Posterior Lamellar Keratoplasty Modalities: DLEK vs. DSEK

Purpose

To compare clinical outcomes after deep lamellar endothelial keratoplasty (DLEK) with Descemet stripping endothelial keratoplasty (DSEK) performed as initial cases by a single surgeon.

Methods

Sixteen patients with corneal endothelial were enrolled. Eight patients (8 eyes) underwent DLEK and 8 patients (8 eyes) DSEK. We measured uncorrected visual acuity, best corrected visual acuity (BCVA), manifest refraction, corneal endothelial count, interface opacity via Schiempflug imaging, and contrast sensitivity, as well as tracked postoperative complications over the first postoperative year.

Results

Primary graft failure occurred in two DLEK cases and one DSEK case, all of which were excluded for further analysis. The average 12-month postoperative BCVA was 20/70 in the DLEK group and 20/50 in the DSEK group, with the difference not statistically significant. No significant differences were identified between the 2 groups in terms of mean spherical equivalent and refractive astigmatism, although individuals in the DSEK group tended toward hyperopia. The average endothelial cell count at postoperative month 12 was 1849±494 in the DLEK group and 1643±417 cells/mm² in the DSEK group, representing cell losses of 26.2% and 31.9%, respectively. No significant differences in endothelial cell count or endothelial cell loss were observed between groups. Early postoperative donor disc dislocation occurred in two eyes after DLEK and one eye after DSEK. Interface opacities and contrast sensitivities were similarly not significantly different between groups.

Conclusions

No significant differences in any assessed clinical outcome were observed between individuals undergoing DLEK and DSEK, when performed as initial cases by a single surgeon.     

Retention of good visual acuity in eyes with neovascular age-related macular degeneration and chronic refractory subfoveal subretinal fluid

Purpose

To describe the clinical characteristics of a subset of eyes with neovascular age-related macular degeneration (NVAMD) receiving intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapy which retain good visual acuity despite chronic, persistent subfoveal subretinal fluid (SRF).

Design

Retrospective, observational case series.

Methods

Study eyes were identified from a consecutive series of 186 patients treated with anti-VEGF therapy seen for regular follow-up over a 3-month period. The clinical histories of 10 eyes of 9 patients with NVAMD, chronic subfoveal SRF despite continuous anti-VEGF therapy, and good long-term visual acuity of 20/40 or greater were reviewed. Demographic factors, baseline and final visual acuity, neovascular lesion type, duration of persistent fluid, baseline and final subfoveal choroidal thickness, presence of geographic atrophy, and number of anti-VEGF injections were analyzed.

Results

The mean age of patients was 78 years (range 55–91). The mean duration of persistent fluid was 5.2 years (range 1.3–11.0). Long-term visual acuities remained stable at 20/40 or better in all eyes. All eyes had type 1 (sub-retinal pigment epithelial) neovascularization. Average baseline subfoveal choroidal thickness was 285.3 μm and the average follow-up subfoveal choroidal thickness was 239.7 μm. No eyes had the presence of geographic atrophy. The mean number of injections was 36.5 (range 17–66).

Conclusion

Some eyes with type 1 neovascularization associated with chronic persistent subfoveal subretinal fluid despite continuous intravitreal anti-VEGF therapy may maintain good long-term visual outcomes. We hypothesize that type 1 neovascularization and greater subfoveal choroidal thickness may exert a protective effect on photoreceptor integrity. Further studies are necessary to assess long-term visual prognosis and predictive factors in patients with type 1 neovascularization leading to persistent subretinal fluid that is recalcitrant to anti-VEGF treatment.     

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 µm and 556.24±42.84 µm 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.     

Comparison of Clinical Outcomes of Same-size Grafting between Deep Anterior Lamellar Keratoplasty and Penetrating Keratoplasty for Keratoconus

Purpose

To compare the clinical outcomes between deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) with same-size grafts in patients with keratoconus.

Methods

Medical records of 16 eyes from 15 patients treated from June 2005 through April 2011 were retrospectively reviewed. Patients with contact lens intolerance or who were poor candidates for contact lens fitting due to advanced cone underwent keratoplasty. The transplantations consisted of 11 DALK and 5 PKP with same-size grafting for keratoconus. Best-corrected visual acuity (BCVA), refractive error, corneal topographic profiling, and clinical course were compared between DALK and PKP groups.

Results

The follow-up period was 30 ± 17 months in the DALK group and 45 ± 20 months in the PKP group (p = 0.145). At final follow-up, the DALK and PKP groups achieved a BCVA (logarithm of the minimum angle of resolution) of 0.34 and 0.52, respectively (p = 0.980). Postoperative refractive error and mean simulated keratometric index showed myopic astigmatism in both groups without any statistical difference. Corneal irregularity index measured at 5 mm in the DALK group was less than that of the PKP group at 1-year follow-up (p = 0.021); however, at final follow-up, there was no longer a statistically significant difference. Endothelial cell counts were lower in the PKP group than in the DALK group at final follow-up (p = 0.021).

Conclusions

The optical outcomes of DALK with same-size grafts for keratoconus are comparable to those of PKP. Endothelial cell counts are more stable in DALK compared to PKP.     

Amyloid corneal deposition in corneal buttons of congenital hereditary endothelial dystrophy (CHED) – A clinical and histopathological case series

Purpose

To determine the frequency, pathology and clinical relevance of amyloid deposited in corneas of CHED.

Methods

Clinical and histopathological case series.

Results

Amyloid subepithelial deposition was found in 5 (6.6%) corneal buttons of 75 patients with histopathologically confirmed CHED diagnosis. Clinical findings included history of parental consanguinity, poor vision (ranging from counting fingers from one foot to 3/200), corneal edema, and central whitish subepithelial corneal nodules in all the five cases and positive family history in 4 of 5 cases. The patients underwent PKP at a mean age of 15 years (range 3–22 years). Histological findings included attenuated endothelium (6/6) thickened Descemet’s membrane (6/6), stromal edema (2/6), and subepithelial amyloid deposits (6/6). All patients improved from vision point of view. To date, no recurrence of the amyloid has been seen in the grafts.

Conclusion

Considering the consanguinity, family history, early onset, and bilaterality, this study supports our hypothesis that the amyloid is primary in nature in our patients and indicates a new subtype of autosomal recessive CHED that require further chemical and genetic analysis. This subtype has the same prognosis for PKP as all CHED patients, if not better.     

Femtosecond-UVA-riboflavin (FUR) cross-linking approach to penetrating keratoplasty and anterior lamellar keratoplasty

Purpose

To introduce femtosecond laser wound design combined with riboflavin/ultraviolet light-A (UVA) collagen cross-linking at the wound for penetrating (PKP) and anterior lamellar keratoplasty (ALK). Primary outcomes were intraocular pressure (IOP in mmHg) at burst point for the PKP group, and tensile strength (kPa) until dehiscence for the ALK group.

Methods

Human corneoscleral rims (N = 20) were mounted on artificial anterior chambers. PKP specimens underwent FUR, femtosecond laser-cut without cross-linking, or conventional corneal transplantation. PKP maximum burst IOP with progressive suture removal was assessed by a digital manometer, in triplicate and by three observers. ALK involved whole human globes (N = 10) divided into three groups using a 200-micron, 8 mm diameter donor lenticule, with or without cross-linking. Cross-linked specimens were exposed to UVA light (3 mW/cm² irradiance, 3.4 J, 370 nm wavelength) for 30 min with 0.1% riboflavin (20% Dextran) applied every 2-min. ALK tensile strength was determined using a digital tensiometer.

Results

In PKP, burst IOP was 31.32 mmHg greater for corneas that underwent the UVA-riboflavin treatment than for those that did not (p < 0.05). There was no significant relationship (p = 0.719) established between cut design (femtosecond versus conventional). On multivariate analysis, there was a mean of 15.82 mmHg higher sustainable pressure for each stabilization suture present (p < 0.0001). In ALK, specimens comprised of human donor and human recipient tissue combined with UVA-riboflavin therapy experienced the greatest level of adhesion strength (954.7 ± 290.4 kPa) as shown by the force required to separate the tissues, and compared to non-cross-linked specimens. Electron microscopy of ALK specimens showed non-fused and fused longitudinal cross-linked collagen fibers as well as bridges, densities, attachment plaques and primitive plasmalemmal densities.

Conclusions

Cross-linking effects of the FUR technique enable a stronger graft-recipient adhesion compared to conventional penetrating and anterior lamellar keratoplasty. Electron microscopy enabled visualization of cross-linked interface and potential bonding. The FUR approach may further lead to sutureless transplantation techniques in the future.

Setting/venue

ImagePlus Laser Eye Centre, Winnipeg, and University of Ottawa Eye Institute, Ottawa, Canada.     

Effects of advanced surface ablations and intralase femtosecond LASIK on higher order aberrations and visual acuity outcome

Background/aims

To study the changes in wavefront (ocular) and corneal higher order aberrations (HOAs) and visual acuity (VA) outcome following wavefront-guided advanced surface ablation (ASA) techniques and intralase femtosecond LASIK (iLASIK) in myopia treatment.

Methods

Ocular aberration and corneal topography of 240 eyes in the ASA techniques (this was equally divided into a flap-on group where the epithelial flap was preserved and reapplied to the photoablated stromal bed and a flap-off group when the epithelial flap was discarded during the procedure), and 138 eyes in the iLASIK group were obtained before and 3 months following treatment. The correlation of aberrations with best spectacle-corrected visual acuity was analyzed.

Results

At 3 months, there was statistically significant (P < 0.001) surgically induced increase in spherical aberration (SA) in each of the techniques for both ocular and corneal analysis. iLASIK induced significantly less ocular and corneal HOAs (P < 0.001). The mean manifest refractive spherical equivalent was closer to attempted correction compared to other groups (P < 0.001). Eighty-three eyes (70%) of flap-on, 80 (67%) flap-off and 94 eyes (68%) in the iLASIK group achieved 20/20 uncorrected VA. Fifteen eyes (11%) accomplished 20/12.5 or better in iLASIK compared to 4 (3%) for flap-on and 7 (6%) for flap-off ASA group. Only the flap-off treatment showed a consistent correlation between the corrected aberrations and visual performance.

Conclusion

At 3 months, all procedures resulted in a significant increase in HOAs and SA. All had comparable 20/20 VA and 11% of iLASIK patients achieved 20/12.5 or better level.     

Corneal graft rejection in African Americans at Howard University Hospital

Purpose

There is scarcity of data in the literature on cornel graft rejection rate in patients exclusively of African ancestry. The purpose of this study was to evaluate the rejection rate of corneal transplant surgery performed at Howard University Hospital on such patients over a 15 year period.

Design

A retrospective evaluation was performed of the cornea graft rejection and corneal graft failure rate in 125 penetrating keratoplasties (PKPs) done by one corneal specialist at Howard University Hospital from January 1, 1990 to August 31, 2005.

Methods

Of the 125 patients, 62 were eliminated from the study because of re-grafted eyes, non-African descent, primary graft failures, follow-up less than 1 month and lack of availability of charts. This study, therefore, studied and recorded data from 63 penetrating keratoplasties of 63 eyes from 60 patients.

Results

Episodes of graft rejection were documented in 23 eyes (36.5% of cases). Nine out of the 23 graft rejections manifested to secondary graft failure (39%). Overall, there were nine out of the 63 PKPs (14.3%) that resulted in secondary graft failure over the past 15 years. The major diagnostic categories were bullous keratopathy 24 (38%), keratoconus 10 (15.8%), Fuch’s dystrophy 4 (6.3%), other 20 (31.7%). Of the cases with episodes of rejection and failure, 4.3% and none were attributable to keratoconus, 30.4% and 22.2% for bullous keratopathy, and 8.7% and 22.2% for Fuch’s dystrophy, respectively. Also, best visual acuity was looked at in patients with rejection episodes. None of the patients had a pre-op visual acuity 20/40 or better; however, post-op PKP 2 (8.7%) of patients achieved 20/40 or better. Also, 4 (17.4%) of patients had a pre-op visual acuity between 20/50 and 20/150, but post-op PKP best visual acuity between 20/50 and 20/150 was increased to 9 (39.1%).

Conclusion

At 36% the prevalence of corneal graft rejection was one of the highest in the reported literature. But only 14% of those episodes resulted in graft failure which is one of the lowest in the published literature. This study demonstrates that patients of African ancestry may have a higher rejection rate which does not necessarily result in graft failure.     

Corneal endothelium after deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus: a four-year comparative study

Purpose:

To compare the status of corneal endothelium and central corneal thickness within the first four postoperative years after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in patients with keratoconus.

Materials and Methods:

Thirty-nine eyes (Group A) which had PK and 44 eyes (Group B) which had DALK for the treatment of keratoconus were included in this retrospective study. The endothelial cell density (ECD), the mean endothelial cell area and the coefficient of variation of cell area were assessed with a non-contact specular microscope, and the central corneal thickness (CCT) was measured with an ultrasound pachymeter.

Results:

Mean ECD loss rate at two years was 36.24% in Group A and 18.12% in Group B (P<0.001). Mean ECD loss rate at four years was 47.82% in Group A and 21.62% in Group B (P<0.001). Mean annual ECD loss rate was calculated 14.12% per year in Group A and 5.78% per year in Group B. In the PK group, increase in mean CCT was 15.60% in two years and 15.03% in four years, while in the DALK group, mean CCT increased by 8.05% in two years and 9.31% in four years.

Conclusions:

As the majority of ectatic disorders such as keratoconus occur in young people, long-term endothelial cell survival following treatment with keratoplasty is essential for the long-term visual ability. Our finding that corneal endothelial cell loss in the DALK group occurs at a slower rate than in the PK group suggests DALK as a safer alternative to PK in these selected patients.     

Posterior sub-tenon’s bevacizumab injection in diabetic macular edema; a pilot study

Purpose

To evaluate the short-term results of sub-tenon’s injection of bevacizumab in patients with clinically significant macular edema (CSME).

Methods

In this prospective non-comparative interventional case series, sub-tenon’s injection of 2.5 mg/0.1 ml bevacizumab was performed for eyes with CSME. Macular thickness and best corrected visual acuity measurements were performed before and one month after injections.

Results

Nineteen eyes of twelve patients with a mean age of 59.8 ± 5.7 years were evaluated. Thirteen eyes (68.4%) had center-involving macular edema. No significant difference was observed between pre- and post-injection central subfield retinal thickness measurements (P = 0.3). Central subfield thickness measurements improved or remained unchanged in 13 eyes (68.4%). Baseline BCVA of 0.48 ± 0.35 LogMAR improved to 0.36 ± 0.26 LogMAR after injection (P = 0.01). Improvement of >2 lines in BCVA was found in 5 eyes (26.3%), and no eye lost >2 lines of BCVA. No complication associated with sub-tenon’s injection was observed.

Conclusion

Sub-tenon’s injection of bevacizumab resulted in significant short-term visual improvement in eyes with CSME. Retinal thickness changes were not significant.     

Anterior Segment Optical Coherence Tomography: Assisted Topographic Corneal Epithelial Thickness Distribution Imaging of a Keratoconus Patient

Purpose

To evaluate safety, efficacy and ease of measurement of epithelial thickness in a keratoconic patient based on anterior segment optical coherence tomography (AS-OCT).

Methods

A 25-year-old male patient, previously diagnosed with keratoconus, with highly asymmetric manifestation among the two eyes, was subjected to AS-OCT corneal epithelial imaging. We investigated epithelial thickness and epithelial topographic thickness distribution.

Results

Mean epithelial thickness was 51.97 ± 0.70 for the less affected right eye (OD), and 55.65 ± 1.22 for the more affected left eye (OS). Topographic epithelial thickness variability for the OD was 1.53 ± 0.21 μm, while for the OS it was 9.80 ± 0.41 μm.

Conclusions

This case further supports our previous findings with high-frequency ultrasound measurements of the increase in overall epithelial thickness in keratoconic eyes in comparison with normal eyes. AS-OCT further offers ease of use and possibly higher predictability of measurement. This case report, based on AS-OCT imaging, verifies increased overall epithelial thickness in keratoconic eyes, as introduced by a previous study [Kanellopoulos et al.: Clin Ophthalmol 2012;6:789–800], based on high-frequency scanning ultrasound biomicroscopy imaging.Key words: Anterior segment optical coherence tomography, Keratoconus, Epithelial imaging, Pentacam HR