Visual Function and Higher-Order Aberrations in Eyes After Corneal Transplantation: How to Improve Postoperative Quality of Vision

In Vivo Imaging and Evaluation of Corneal Biomechanics After Corneal Transplantation by Optical Coherence Elastography

Postoperative corneal biomechanical evaluation is of great significance in clinical monitoring and management since corneal transplantation is one of the main methods to improve visual function. In this paper, we propose an OCE system based on a small ultrasound transducer to realize the in vivo detection of postoperative corneal elasticity in different directions. It was first validated and analyzed by different agar, and then the elasticity changes in normal cornea and post-transplant corneal implants and implant beds were further investigated. Compared with normal corneas, the shear wave velocity of the postoperative cornea decreased from 7.42 ± 1.71 m/s to 4.95 ± 0.35 m/s. Meanwhile, the shear wave velocity of the corneal implant bed was lower than that of the implanted sheet. Therefore, this study reports the first biomechanical measurement of corneal grafts based on the OCE technique, which might provide a potential tool for the postoperative evaluation of clinical patients.

Risk Factors for Corneal Monochromatic Aberrations and Implications for Multifocal and Extended Depth-of-Focus Intraocular Lens Implantation

PURPOSE

To discuss factors influencing corneal aberrations that might influence the optical quality after intraocular lens (IOL) implantation.

METHODS

PubMed and Scopus were the main resources used to search the medical literature. An extensive search was performed to identify relevant articles concerning factors influencing the level of corneal aberrations as of August 27, 2023. The following keywords were used in various combinations: corneal, aberrations, defocus, astigmatism, spherical aberration, coma, trefoil, quadrafoil, intraocular lens, and IOL.

RESULTS

Conclusive evidence is lacking regarding the correlation between age and changes in corneal aberrations. Patients with astigmatism have greater corneal higher-order aberrations than those with minimal astigmatism, particularly concerning trefoil and coma. Increased levels of corneal higher-order aberrations are noted following contact lens wear, in patients with dry eye disease, and with pterygium. Increased higher-order aberrations have been reported following corneal refractive surgery and for 3 months following trabeculectomy; regarding intraocular lens surgery, the results remain controversial.

CONCLUSIONS

Several factors influence the level of corneal higher-order aberrations. Multifocal and extended depth-of-focus IOLs can share similarities in their optical properties, and the main difference arises in their design and performance with respect to spherical aberration. Preoperative evaluation is critical for proper IOL choice, particularly in corneas with risk of high levels of aberrations. [J Refract Surg. 2024;40(6):e420-e434.].

Pupil versus 1st Purkinje capsulotomy centration with femtosecond laser: Long term outcomes with a sinusoidal trifocal lens

PURPOSE

To assess the role of femtosecond laser-assisted capsulotomy centration in the long-term intraocular positioning of a multifocal intraocular lens.

DESIGN

Prospective comparative study.

METHODS

A total of 60 eyes of 30 patients underwent femtosecond laser-assisted Refractive Lens Exchange (RLE). For every patient, capsulotomy centration was randomly performed according to pupil centre (PC) in one eye and first Purkinje reflex (FPR) in the other. The intraocular lens (IOL) positioning, visual acuities, spherical equivalent, internal aberrometry and quality of vision were assessed and compared at 3 years' follow-up between groups (PC and FPR).

RESULTS

Intraocular lens positioning showed a statistically significant difference between groups, with a closer centration to the visual axis in the FPR patients (p < 0.001). Internal aberrometry showed higher values in the PC capsulotomy centration group (p < 0.01).

CONCLUSIONS

FPR centered capsulotomy is associated to a closer centration of the IOL to the visual axis.

Refractive outcomes after DMEK: meta-analysis

In this meta-analysis and systematic literature review of refractive outcomes after Descemet membrane endothelial keratoplasty (DMEK), the extent of the refractive shift and an overview of reasons for refractive shift after DMEK are provided. The PubMed library was screened for articles containing the terms "Descemet membrane endothelial keratoplasty," "DMEK," "Descemet membrane endothelial keratoplasty combined with cataract surgery," "triple-DMEK" combined with "refractive outcomes," "refractive shift," and "hyperopic shift." The refractive outcomes after DMEK were analyzed and compared using a fixed and random effects model. The overall mean change of the spherical equivalent outcome when compared with the preoperative value in cases of DMEK or when compared with the preoperative target refraction in cases of DMEK combined with cataract surgery was +0.43 diopters (D) (95% CI, 0.31-0.55). When DMEK is combined with cataract surgery, a target refraction of -0.5 D is recommended to achieve emmetropia. Changes in the posterior corneal curvature are identified as the main cause of the refractive hyperopic shift.

A novel pupilloplasty in crescent-shaped suturing pattern for coloboma and traumatic iris defects

OBJECTIVE

PURPOSE: To observe the safety and effect of the C-pupilloplasty for the treatment of iris coloboma and traumatic iris defects.

METHODS

A total of 21 cases (21 eyes) with iris coloboma or traumatic iris defects who underwent C-pupilloplasty (a single-pass three-throw technique) from Feb. 2016 to Mar. 2020 were analyzed retrospectively. Uncorrected visual acuity, refraction, corneal topographic keratometry and endothelial cell density were examined.

RESULTS

All the patients were successfully treated, and a central and round pupil was restored. The mean follow-up duration was 8.76 ± 3.58 months (ranging from 2 to 14 months). All patients had round or round-like pupils with a diameter less than or equal to 3 mm after the C-pupilloplasty. Very slightly endothelial loss, negligible symptoms such as glare, distortion, dizziness and photophobia were observed.

CONCLUSION

We introduced a new technique of pupilloplasty (C-pupilloplasty) which could be a more straight forward and more effective treatment for iris coloboma and traumatic iris defect.

Investigation of contrast visual acuity with rigid gas permeable contact lenses after penetrating Keratoplasty

BACKGROUND

To investigate the effects of rigid gas permeable contact lens (RGP-CL) wear on contrast visual acuity in patients after penetrating keratoplasty.

METHODS

Nineteen patients (19 eyes), aged 30.45 ± 5.83 years, who had received penetrating keratoplasty and were successfully fitted with RGP-CLs at our hospital from July 2017 to June 2018 were included. Contrast visual acuities at 100%, 25%, and 10% with spectacles and RGP-CLs were analyzed using the Chi-square test. The wavefront aberrations at the anterior surface of the cornea before and 1 month after RGP-CL wear were compared using the matched sample t-test.

RESULTS

The mean best spectacle-corrected visual acuities were 0.390 ± 0.135 logMAR, 0.706 ± 0.182 logMAR, and 0.952 ± 0.223 logMAR at the 100%, 25%, and 10% contrast levels, respectively, which were significantly lower than the RGP-CL-corrected visions at the three levels (0.255 ± 0.133 logMAR, 0.488 ± 0.168 logMAR, and 0.737 ± 0.159 logMAR; all P < 0.001). The vision losses with RGP-CLs were 0.231 ± 0.099 logMAR and 0.466 ± 0.094 logMAR at the 25% and 10% contrast levels, respectively. The Zernike spherical aberration Z⁰₄ was reduced from 3.734 ± 1.061 μm to 2.622 ± 0.725 μm after wearing the RGP-CLs (P ≤ 0.001). The astigmatism parameters of Z^- 2₂ and Z²₂ were also reduced from 3.761 ± 2.309 μm and 3.316 ± 2.147 μm to 2.637 ± 1.722 μm and 2.016 ± 1.184 μm, respectively (P < 0.05).

CONCLUSION

For post-keratoplasty patients, RGP-CLs can help to improve visual performance, especially low contrast visual acuity. The improvement may be related to the reduction of corneal aberrations, mainly the spherical and astigmatism aberrations.

Agreement between anterior segment swept source-OCT and Scheimpflug imaging corneal aberration measurements in healthy eyes

PURPOSE

To assess agreement between corneal aberration measurements made through swept-source optical coherence tomography using a new anterior segment imaging device (Anterion) and a Scheimpflug imaging device (Pentacam HR) in healthy subjects.

METHODS

Cross-sectional study. In 50 eyes of 50 healthy subjects, 14 aberration parameters (7 across the anterior corneal surface and 7 across the total surface) were measured in 4 mm and 6 mm optic zones using each device: oblique trefoil (Z3_-3), vertical coma (Z3_-1), horizontal coma (Z3_1), horizontal trefoil (Z3_3), spherical aberration (Z4_0), root mean square (RMS) lower order aberrations (LOA) and RMS higher order aberrations (HOA). Data for the two devices were compared through intraclass correlation coefficients (ICC), paired t tests, limits of agreement (LoA) and Bland Altman plots.

RESULTS

Vertical coma was the only corneal aberration parameter that consistently showed excellent agreement (ICC > 0.8, mean difference -0.019, LoA -0.165 to 0.126). Good agreement (ICC = 0.75) between the devices was observed for RMS HOA, but this was slightly worse in the 6 mm optical zone (ICC = 0.667 for anterior RMS HOA). No over- or underestimation trend by one or other device was noted. Agreement was poor to moderate for the rest of the corneal parameters (ICC 0.2 to 0.7).

CONCLUSION

Despite good agreement overall for vertical coma and RMS HOA values, agreement for the remaining corneal aberration measurements was poor to moderate. As mean differences in our sample were overall small, in normal eyes these devices could be clinically judged as interchangeable.

A Multicenter Study of the Distribution Pattern of Posterior-To-Anterior Corneal Curvature Radii Ratio in Chinese Myopic Patients

Estimation of corneal refractive power (CRP) is of crucial importance to refractive and cataract surgery. The ratio of posterior to anterior curvature radii of the cornea (P/A ratio) is one of the key factors to determine the actual CRP (True-K). While the traditional method to calculate the CRP (Sim-K) is based on a constant P/A ratio (0.82), it is suggested that the P/A ratio varies in different people and exhibits a distribution pattern, which may have an impact on the accuracy of CRP estimation and postoperative refractive outcome. In this multicenter study, we aimed to investigate the distribution pattern of the P/A ratio in a large number of myopic patients, and further explore the relationship between P/A ratio and ΔK (the difference between True-K and Sim-K). We found that distribution of the P/A ratio ranged from 0.72 to 0.86 with an average value of 0.82 ± 0.01. The compensation effect of the refractive power of the posterior on the anterior surface of the cornea decreased with the increase of P/A ratio. There was a significant correlation between P/A ratio and ΔK in all eyes (r = 0.9764, P &lt; 0.0001). A change of 0.1 in P/A ratio could cause a change of 0.75 D in ΔK. Our study suggests that the actual P/A ratio should be taken into consideration in refractive and cataract surgery when calculating the CRP and power of the intraocular lens in eyes with significantly deviated P/A ratios.

Post-penetrating keratoplasty astigmatism

Postoperative astigmatism is one of the common complications affecting visual outcomes after a penetrating keratoplasty. It can result from various factors related to host, donor and surgical technique, resulting in suboptimal visual outcome. While some of the measures taken during preoperative planning and during actual surgery can reduce the magnitude of postoperative astigmatism, postoperative correction of astigmatism is often required in cases with high degrees of astigmatism. When spectacles and contact lenses fail to provide optimal visual outcomes, various surgical techniques that include astigmatic keratotomy, compression sutures, toric intraocular lens placement, and laser refractive procedures can be considered. When none of these techniques are able to achieve a desired result with in the acceptable optical range, a repeat keratoplasty is considered a last option. We discuss the various causes and management of complication of postoperative astigmatism occurring after a full thickness corneal transplantation surgery.

Quality of vision and vision-related quality of life after Descemet membrane endothelial keratoplasty: a randomized clinical trial

Purpose

To compare quality of vision and vision‐related quality of life (QOL) in patients undergoing Descemet membrane endothelial keratoplasty (DMEK) or ultrathin Descemet stripping automated endothelial keratoplasty (DSAEK).

Methods

Fifty‐four eyes of 54 patients with Fuchs' dystrophy from six corneal clinics in the Netherlands were randomized to DMEK or ultrathin DSAEK and examined preoperatively, and 3, 6 and 12 months postoperatively. Main outcome measures were corneal higher‐order aberrations (HOAs), contrast sensitivity, straylight and vision‐related QOL.

Results

Posterior corneal HOAs decreased after DMEK and increased after ultrathin DSAEK (p ≤ 0.001) 3 months after surgery and correlated positively with best spectacle‐corrected visual acuity (12 months: r = 0.29, p = 0.04). Anterior and total corneal HOAs did not differ significantly between both techniques at any time point. Contrast sensitivity was better (p = 0.01), and straylight was lower (p = 0.01) 3 months after DMEK compared with ultrathin DSAEK; 95% confidence interval [CI] of log(cs) 1.10–1.35 versus 95% CI: 0.84 to 1.12, and 95% CI: log(s) 1.18 to 1.43 versus 95% CI: 1.41 to 1.66, respectively. Both were comparable at later time points. Vision‐related QOL (scale 0–100) did not differ significantly between both groups at any time point and improved significantly at 3 months (β = 12 [95% CI: 7 to 16]; p < 0.001), and subsequently between 3 and 12 months (β = 5 [95% CI: 0 to 9]; p = 0.06).

Conclusions

Descemet membrane endothelial keratoplasty (DMEK) results in lower posterior corneal HOAs compared with ultrathin DSAEK. Contrast sensitivity and straylight recover faster after DMEK but reach similar levels with both techniques at 1 year. Vision‐related QOL improved significantly after surgery, but did not differ between both techniques.

[Comparative assessment of functional outcomes of different endothelial keratoplasty techniques]

PURPOSE

Comparative analysis of the higher-order aberrations (HOA) of the cornea after endothelial keratoplasty (EK) using DSAEK and DMEK techniques; evaluation of the correlation between higher-order corneal aberrations and functional outcomes of the treatment.

MATERIAL AND METHODS

The study included 47 patients (59 eyes). The main group consisted of 35 patients (35 eyes) with bullous keratopathy and Fuchs' endothelial dystrophy; among them, 19 patients underwent endothelial keratoplasty using the DSAEK technique and 16 - DMEK technique. The control group included 12 patients (24 eyes) of corresponding age without corneal pathology. Standard and special examination tests were performed before, as well as 6 and 12 months after the operation, including computed tomography and aberrometry of the cornea using the Pentacam HR system. Same tests were performed in the control group.

RESULTS

The values of the main HOA of the anterior corneal surface: RMS coma (Z₃^±1, Z₅^±1), RMS spherical aberration (SA; Z₄⁰, Z₆⁰) and RMS HOA (Z_3-6) 6 months after different EK techniques were statistically significantly higher than in the control group. A statistically significantly lower induction of aberrations of the posterior corneal surface after DMEK technique was revealed. Analysis of the final aberration pattern 6 months after surgery did not reveal any statistically significant differences in the values of the main (RMS coma, RMS SA, RMS HOA) total corneal aberrations after DSAEK and DMEK. A negative correlation was revealed between the best corrected visual acuity (BCVA) and HOA; however, it was statistically significant only for individual aberration values: RMS HOA (Z_3-6) of the posterior corneal aberrations after DMEK (r= -0.634, p=0.049), and RMS coma (Z₃^±1, Z₅^±1) of the cornea after DSAEK (r= -0.57, p=0.042).

CONCLUSION

Comparative analysis of total corneal HOA did not reveal a statistically significant difference in the main parameters: RMS coma, RMS SA, RMS HOA in patients after DSAEK and DMEK surgeries. Correlation analysis did not reveal any statistically significant effects of most aberrations on the functional outcomes of the treatment.

Refractive Outcomes After Descemet Membrane Endothelial Keratoplasty + Cataract/Intraocular Lens Triple Procedure: A Fellow Eye Comparison

PURPOSE

Descemet membrane endothelial keratoplasty is often combined with phacoemulsification and intraocular lens implantation (DMEK + cataract/IOL triple procedure) in phakic patients. This procedure results in a refractive shift that is difficult to predict. The aim of this study was to evaluate the hypothesis that the refractive shift in the second eye follows the shift in the first eye.

METHODS

In this retrospective, single-center, consecutive case series, the refractive outcomes of 254 eyes of 127 patients who underwent DMEK + cataract/IOL triple procedure in both eyes for Fuchs endothelial corneal dystrophy have been analyzed. Main outcome measures were spherical equivalent outcome (shift calculations), best spectacle-corrected visual acuity, central corneal thickness, and posterior simulated keratometry.

RESULTS

The mean best spectacle-corrected visual acuity before surgery was 0.51 ± 0.24 and increased to 0.19 ± 0.15 (logMAR) after surgery (P < 0.001). After surgery, a mean hyperopic shift of 0.98 ± 0.89 D was observed. The refractive shift was 1.03 ± 0.93 D and 0.92 ± 1.02 D, in the first and second eyes, respectively (P = 0.435). In a paired analysis, the mean difference of the refractive shift between the first and second eyes was 0.49 ± 0.43 D.

CONCLUSIONS

In our fellow eye comparison, the refractive shift after DMEK + cataract/IOL triple procedure in the second eye was comparable with the shift in the first eye. As a consequence, the refractive outcome of the first eye might serve as a reference for optimizing the refractive target in the second eye. Further studies investigating the influence of corneal parameters on refractive shift are needed for a more predictable lens power selection.

[Methods of surgical treatment of keratectasia and analysis of postsurgical quality of vision]

Keratectasias are non-inflammatory dystrophic diseases of the cornea characterized by progressive bilateral thinning of the cornea that lead to deterioration in the quantitative and qualitative characteristics of vision reducing patient's quality of life. The changes can be asymmetrical and destructive. A number of surgeries have been proposed to reduce the negative effects of keratectasia including penetrating keratoplasty and its modifications, implantation of corneal ring segments, corneal cross-linking - alone and in combination with other methods, intrastromal keratoplasty. These methods can improve visual acuity to a certain degree and help slow the progression of keratectasia. This article studies various surgical methods used for treating keratectasia and analyses possible assessment of the quality of vision before and after the treatment.

Optical characteristics after Descemet membrane endothelial keratoplasty: 1-year results

PURPOSE

To evaluate the corneal characteristics after Descemet membrane endothelial keratoplasty (DMEK) compared with normal corneas.

METHODS

Patients who underwent DMEK at Yokohama Minami Kyosai Hospital were included and prospectively evaluated pre-operatively and at postoperative months 1, 3, 6, and 12, and compared to healthy controls. Corneal characteristics evaluated included corneal curvature (keratometric value [KV]; D), central corneal thickness (CCT), peripheral corneal thickness (PCT), and corneal higher-order aberrations [HOAs] at 6.0 mm diameter, calculated by anterior segment optical coherence tomography and logarithm of the minimal angle of resolution [logMAR].

RESULTS

A total of 30 eyes of 30 patients (6 men, 24 women, mean age 73.4 ± 7.4 years) were included and compared with 31 age-matched healthy control eyes (13 men, 18 women; mean age 73.0 ± 6.7 years). LogMAR after DMEK improved from 0.87 ± 0.07 preoperatively to 0.04 ± 0.07 at 12 months postoperatively (p<0.001). Although anterior KVs of DMEK eyes were similar to those of control eyes, posterior KVs were significantly larger (-6.4 ± 0.3 D vs. -6.3 ± 0.2 D; p = 0.02). Total HOAs after DMEK improved from 1.94 ± 1.05 μm preoperatively to 1.05 ± 0.16 μm at 12 months postoperatively (p<0.001), which was significantly higher than that in control eyes (0.63 ± 0.06) (p<0.001). Despite the similar CCTs in the two groups, the PCT was significantly larger in DMEK eyes (704 ± 41 μm vs 669 ± 38 μm, p = 0.002) at 12 months.

CONCLUSION

Despite achieving good visual function and excellent corneal clarity, eyes that underwent DMEK showed a steeper posterior KV and higher corneal HOAs than normal eyes even at 12 months after surgery.

Ultrathin Descemet stripping automated endothelial keratoplasty versus Descemet membrane endothelial keratoplasty: a fellow-eye comparison

Background

To compare the visual outcome and patients’ satisfaction after ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) and Descemet membrane endothelial keratoplasty (DMEK) performed on fellow eyes of the same patients.

Methods

In this retrospective study, the records of 18 pseudophakic patients affected by Fuchs endothelial dystrophy who underwent DMEK in one eye and UT-DSAEK in the fellow eye were reviewed. Best corrected visual acuity (BCVA), corneal pachymetry, keratometry, corneal aberrations, photopic and mesopic contrast sensitivity, and endothelial cell counts measured 12 months after surgery in either eye were analyzed and compared. The results of a satisfaction questionnaire were also reviewed.

Results

Twelve months after surgery, BCVA was not significantly different in UT-DSAEK and DMEK eyes (0.10 ± 0.04 and 0.07 ± 0.07 logMAR, respectively); at both 4- and 6 mm optical zones total and posterior corneal higher order aberrations (HOAs), posterior astigmatism and total coma were significantly lower after DMEK; BCVA in both groups was significantly correlated mainly with anterior corneal aberrations; contrast sensitivity was higher after DMEK especially in mesopic conditions and at medium spatial frequencies; the endothelial cell density was similar, although slightly higher in the UT-DSAEK group (p = 0.10). The satisfaction questionnaire showed that although patients were highly satisfied from both procedures, more than half of them preferred DMEK and reported a more comfortable and quicker postoperative recovery.

Conclusions

DMEK and UT-DSAEK showed no evidence of difference in terms of postoperative BCVA, although DMEK had a better performance in terms of contrast sensitivity, posterior corneal aberrations and overall patient satisfaction.

Correlation and predictability of ocular aberrations and the visual outcome after quadrifocal intraocular lens implantation: a retrospective longitudinal study

Background

To evaluate the correlating and predicting factors of visual outcome after implantation of newly developed diffractive quadrifocal intraocular lens (IOL).

Methods

A retrospective longitudinal study was conducted. Patients who underwent diffractive quadrifocal IOL implantation with a follow-up period longer than six months and records of wavefront aberrometer within one week perioperatively were enrolled. Accordingly, a total of 73 eyes from 73 patients were included. The postoperative distance and near visual acuity, ocular aberrations and postoperative symptoms were collected. The correlation and predictability between ocular aberrations and the postoperative visual outcome were evaluated.

Results

The corrected distance visual acuity (CDVA) one month postoperatively was significantly better than the preoperative status, and insignificant improvement was found six months postoperatively. Preoperative Tracey refraction spherical equivalent (TRSE), angle alpha, and spherical aberration (SA) were significantly correlated with postoperative CDVA and near corrected visual acuity (NCVA). For postoperative ocular aberrations, TRSE, angle alpha, and SA were significantly correlated with CDVA six months postoperatively and NCVA, while the trefoil, internal higher order aberration (HOA) and total HOA were associated with NCVA. Preoperative angle alpha could predict all postoperative visual performances, while postoperative TRSE and angle alpha could predict the CDVA six months postoperatively and NCVA. A large angle alpha is associated with visual disturbance and dissatisfaction.

Conclusion

The angle alpha preoperatively and postoperatively was correlated with the postoperative vision and could predict visual outcome in patients who had diffractive quadrifocal IOL implanted. Furthermore, the majority of ocular aberrations were also associated with certain postoperative vision.

Impact of Corneal Higher-Order Aberrations on Visual Acuity After Deep Anterior Lamellar Keratoplasty in Treating Keratoconus

PURPOSE

To evaluate the incidence of the Descemet membrane (DM) folds after deep anterior lamellar keratoplasty (DALK) in treating keratoconus. We also evaluated the influence of DM folds and corneal higher-order aberrations (HOAs) on visual acuity after DALK.

METHODS

This retrospective study included 89 consecutive eyes of 87 patients who underwent DALK for the treatment of keratoconus at Tokyo Dental College Ichikawa General Hospital from April 2002 to June 2017. The presence or absence of DM folds was determined by slitlamp microscopy. Visual acuity after DALK was compared between the eyes with and without DM folds. Corneal HOAs of the anterior and posterior surfaces and the total cornea were measured by anterior segment optical coherence tomography. Correlations among the presence of DM folds, corneal HOAs, and visual acuity were analyzed.

RESULTS

The Descemet membrane folds developed in 28.1% (25/89) eyes after DALK for the treatment of keratoconus. However, there were no significant differences in postoperative visual acuity between the eyes with and without DM folds at 1, 3, 6, and 12 months (P=0.739, P=0.106, P=0.223, and P=0.186, respectively). The visual acuity at 12 months was significantly correlated with corneal HOAs within a 4-mm diameter (anterior surface: R=0.546, P=0.003; total cornea: R=0.506, P=0.007).

CONCLUSIONS

Larger corneal HOAs, but not the presence of DM folds, were associated with poor visual acuity after DALK. In treating advanced keratoconus with DALK, it is important to minimize postoperative corneal HOAs, although DALK improves visual acuity by reducing HOAs due to keratoconus.

Can we predict the refractive outcome after triple Descemet membrane endothelial keratoplasty?

Purpose:

To analyze and correlate corneal parameters with refractive shift after Descemet membrane endothelial keratoplasty combined with cataract surgery (triple Descemet membrane endothelial keratoplasty).

Methods:

This single-center retrospective observational case series included 152 eyes of 152 consecutive patients undergoing triple Descemet membrane endothelial keratoplasty in the first eye for Fuchs endothelial corneal dystrophy. Patients were examined preoperatively, as well as at 3, 6, and 12 months after surgery. The main outcome measures were: refractive shift (predicted refractive outcome based on intraocular lens calculation compared to actual postoperative refractive outcome), central corneal thickness, corneal volume, anterior and posterior corneal curvature, and corneal densitometry. These parameters were analyzed and correlated with the refractive shift after surgery.

Results:

After 3 months from surgery, a mean refractive shift of +1.12 ± 1.10 D was observed and remained stable until the last follow-up at 12 months (+1.24 ± 1.07 D). Correlation analysis showed a weak but significant positive correlation between refractive shift and preoperative posterior curvature (rho = 0.314; p = 0.002) or preoperative posterior densitometry (rho = 0.227; p = 0.008). No correlation was found between refractive shift and preoperative central corneal thickness, corneal volume, anterior curvature, or anterior/mid-cornea densitometry.

Conclusion:

Changes of the posterior cornea may have an influence on the refractive shift. Patients with flatter posterior corneal curvature or higher posterior corneal density seem to exhibit a higher hyperopic shift. The weak correlations indicate a poor predictive value of any preoperative parameter used in our study.

Corneal Higher-order Aberrations and Visual Improvement Following Corneal Transplantation in Treating Herpes Simplex Keratitis

PURPOSE

To examine corneal higher-order aberrations (HOAs) and visual improvement following corneal transplantation in treating corneal scar caused by herpes simplex keratitis (HSK).

DESIGN

Retrospective consecutive case series.

METHODS

This study included a total of 52 eyes: 18 eyes of normal subjects, and 34 eyes of consecutive patients with corneal scar owing to HSK who underwent penetrating keratoplasty (PKP, 17 eyes) or deep anterior lamellar keratoplasty (DALK, 17 eyes). HOAs of the anterior, posterior surfaces and the total cornea were analyzed by anterior segment optical coherence tomography. The correlations between corneal HOAs and visual improvement were also analyzed.

RESULTS

Mean logarithm of the minimal angle of resolution (logMAR) visual acuity significantly improved from 1.40 ± 0.70 to 0.46 ± 0.45 after corneal transplantation (P < .0001). Mean corneal HOAs of the anterior surface significantly decreased after corneal transplantation (PKP: from 1.16 ± 0.59 μm to 0.58 ± 0.35 μm, P = .035, DALK: from 0.94 ± 0.57 μm to 0.37 ± 0.18 μm, P = .004). Visual acuity following corneal transplantation was correlated with the corneal HOAs at 12 months (r = 0.53, P = .01). Visual improvement at 3, 6, and 12 months was positively correlated with preoperative HOAs of the total cornea and posterior surface (all P < .01).

CONCLUSIONS

Preoperative corneal HOAs were associated with the visual improvement in treating corneal scar caused by HSK. Thus, the preoperative assessment of corneal HOAs, especially of the posterior surface, is important in the decision to perform corneal transplantation in eyes with HSK.

Topographic characteristics after Descemet's membrane endothelial keratoplasty and Descemet's stripping automated endothelial keratoplasty

PURPOSE

To investigate the topographic characteristics of the posterior corneal surface after Descemet's endothelial membrane keratoplasty (DMEK) and Descemet's stripping automated endothelial keratoplasty (DSAEK) and their effects on postoperative visual acuity.

METHODS

Nineteen eyes of 19 patients after DMEK, 23 eyes of 23 patients after DSAEK, and 18 eyes of 18 control subjects were retrospectively analyzed. Best spectacle-corrected visual acuity (BSCVA), aberration factors (higher-order aberrations [HOAs], spherical aberrations [SAs], and coma aberrations [Comas] at 6.0 mm) were evaluated preoperatively and at 1, 3, and 6 months postoperatively. The posterior refractive pattern of the topography map was classified into 5 grades (0-5) (posterior color grade) using anterior segment optical coherence tomography. Correlations between BSCVA and some factors (abbreviation factors, posterior color grade) were analyzed.

RESULTS

BSCVA was significantly better after DMEK than after DSAEK (P < 0.001). Posterior HOAs, SAs, and Comas after each type of endothelial keratoplasty were significantly greater compared to control (P < 0.01). Posterior HOAs, total/anterior/posterior SAs, and posterior color grade were significantly lower in the DMEK group than in the DSAEK group at 3 months (P < 0.024 [posterior HOAs], P = 0.047 [total SA], P < 0.001 [anterior SAs], P = 0.021 [posterior SAs], and P < 0.001 [posterior color grade]) and 6 months postoperatively (P = 0.034 [posterior HOAs], P < 0.001 [total SAs], P < 0.001 [anterior SAs], P = 0.013 [posterior SAs], and P = 0.004 [posterior color grade]). BSCVA was significantly correlated with HOAs, SAs, and posterior color grade (P < 0.001 for all except anterior HOAs [P = 0.004]).

CONCLUSIONS

High posterior color grades were associated with larger aberration factors and had a negative effect on visual function after endothelial keratoplasty. Rapid improvement of visual function after DMEK may be attributed to less change at the posterior surface.

Shifting trends in microbial keratitis following penetrating keratoplasty in Taiwan

To investigate the clinical and microbiological profiles from microbial keratitis following penetrating keratoplasty (PKP) in a tertiary referral center in Taiwan, the medical records of 648 consecutive patients (648 eyes) undergoing PKP between January 2003 and December 2007 were retrospectively reviewed. Patients who subsequently sustained microbial keratitis were enrolled and analyzed for potential risk factors, clinical manifestations, microbiological profiles, complications, graft survival, and final visual outcome. A total number of 42 corneal graft infections (6.5%) were recruited. Mean interval between corneal transplantation and graft infection was 12 ± 9.5 months. Potential risk factors included suture-related problems (31.0%), lid abnormalities (23.8%), persistent epithelial defect (23.8%), contact lens use (14.3%), dry eye (11.9%), and prior rejection episodes (4.8%). Lesions were discovered mostly at the donor-recipient junction ([DRJ] 45.2%). Positive cultures were identified in all of the morbid eyes, of which Pseudomonas aeruginosa was the most common pathogen (38.1%). Despite mandatory hospitalization and topical fortified antibiotics management, complications ensued such as graft failure (71.4%), hypopyon (21.4%), corneal perforation (14.3%), wound dehiscence (11.9%), and endophthalmitis (4.8%). The visual outcome was dismal that graft clarity was achieved in only 12 eyes (28.6%), and that final visual acuity deteriorated to less than 20/200 in 28 eyes (66.7%). In conclusion, microbial keratitis following PKP is a devastating event that severely impairs graft survival rate and postoperative visual outcome which usually occur within the first postoperative year. The incidence of post-PKP microbial keratitis has generally decreased in recent years whilst P. aeroginosa prevails as the leading cause of graft infection in our hospital. Close follow-up by ophthalmologists and elevated self-awareness of patients for at least one year are always encouraged to prevent late-onset infection.