Implementing and evaluating a fully functional AI-enabled model for chronic eye disease screening in a real clinical environment

BACKGROUND

Artificial intelligence (AI) has the potential to increase the affordability and accessibility of eye disease screening, especially with the recent approval of AI-based diabetic retinopathy (DR) screening programs in several countries.

METHODS

This study investigated the performance, feasibility, and user experience of a seamless hardware and software solution for screening chronic eye diseases in a real-world clinical environment in Germany. The solution integrated AI grading for DR, age-related macular degeneration (AMD), and glaucoma, along with specialist auditing and patient referral decision. The study comprised several components: (1) evaluating the entire system solution from recruitment to eye image capture and AI grading for DR, AMD, and glaucoma; (2) comparing specialist's grading results with AI grading results; (3) gathering user feedback on the solution.

RESULTS

A total of 231 patients were recruited, and their consent forms were obtained. The sensitivity, specificity, and area under the curve for DR grading were 100.00%, 80.10%, and 90.00%, respectively. For AMD grading, the values were 90.91%, 78.79%, and 85.00%, and for glaucoma grading, the values were 93.26%, 76.76%, and 85.00%. The analysis of all false positive cases across the three diseases and their comparison with the final referral decisions revealed that only 17 patients were falsely referred among the 231 patients. The efficacy analysis of the system demonstrated the effectiveness of the AI grading process in the study's testing environment. Clinical staff involved in using the system provided positive feedback on the disease screening process, particularly praising the seamless workflow from patient registration to image transmission and obtaining the final result. Results from a questionnaire completed by 12 participants indicated that most found the system easy, quick, and highly satisfactory. The study also revealed room for improvement in the AMD model, suggesting the need to enhance its training data. Furthermore, the performance of the glaucoma model grading could be improved by incorporating additional measures such as intraocular pressure.

CONCLUSIONS

The implementation of the AI-based approach for screening three chronic eye diseases proved effective in real-world settings, earning positive feedback on the usability of the integrated platform from both the screening staff and auditors. The auditing function has proven valuable for obtaining efficient second opinions from experts, pointing to its potential for enhancing remote screening capabilities.

TRIAL REGISTRATION

Institutional Review Board of the Hamburg Medical Chamber (Ethik-Kommission der Ärztekammer Hamburg): 2021-10574-BO-ff.

Safety and Precision of Two Different Flap-morphologies Created During Low Energy Femtosecond Laser-assisted LASIK

Purpose

Currently, two major principles exist to create LASIK flaps: firstly, a strictly horizontal (2D) cut similar to the microkeratome-cut and secondly an angled cut with a "step-like" edge (3D). The strictly horizontal (2D) cut method can be performed using apparatus such as the low-energy FEMTO LDV Z8 laser and its predecessors which are specific to this type. Alternatively, the low-energy FEMTO LDV Z8 laser's 3D flap design creates an interlocking flap-interface surface which potentially contributes toward flap stability. In addition, the FEMTO LDV Z8 offers flap-position adjustments after docking (before flap-creation). The current study analyzed precision, safety, efficacy, as well as patient self-reported pain and comfort levels after applying two different types of LASIK flap morphologies which were created with a low-energy, high-frequency femtosecond (fs) laser device.

Methods

A prospective, interventional, randomized, contralateral eye, single-center comparison study was conducted from November 2019 to March 2020 at the Hamburg vision clinic/ zentrumsehstärke, Hamburg, Germany. Eleven patients and 22 eyes received low-energy fs LASIK treatment for myopia or myopic astigmatism in both eyes. Before the treatment, the eyes were randomized (one eye was treated with the 2D, the other eye with the 3D method).

Results

The mean central flap thickness one month after surgery was 110.7 ± 1.6 μm (2D) and 111.2 ± 1.7 μm (3D); P = 0.365 (2D vs 3D). Flap thickness measured at 13 different points resulted in no statistically significant differences between any of the measurement points within/between both groups; demonstrating good planarity of the flap was achieved using both methods. Despite not being statistically significant, the surgeons recognized an increase in the presence of an opaque bubble layer in the 3D flap eyes during surgery and some patients reported higher, yet not statistically significant, pain scores in the 3D flap eyes during the first hours after the treatment. Overall, safety- and efficacy indices were 1.03 and 1.03, respectively.

Conclusion

In this prospective, randomized, contralateral eye study, the low-energy fs laser yielded predictable lamellar flap thicknesses and geometry at one-month follow-up. Based on these results, efficacy and safety of the corresponding laser application, that is, 2D vs 3D, are equivalent.

Biometry and Intraocular Lens Power Calculation by Combined Scheimpflug-Placido Disc versus Optical Interferometry Devices

Purpose

To compare the results of the current gold standard, laser interferometry, and keratometry by the IOL-Master, with a newly developed Galilei G6 using raytracing software Okulix for intraocular lens (IOL) power calculations.

Methods

For comparison of the IOL-power calculation of both devices, we analyzed the difference between the actual one-month postoperative subjective refraction and the theoretically calculated target refraction before cataract surgery. The IOL was selected according to the IOL Master recommendation aiming for emmetropia after surgery.We analyzed the differences of the measurements of the basic biometric data in 205 healthy eyes by each device.

Results

Our study included 205 healthy, unoperated eyes from 117 patients (61 women, 56 men) aged 20 to 75 years. Twenty-two eyes of cataract patients were also included in this retrospective study design. The mean difference between the prediction of the postoperative refraction and the refraction actually achieved was 0.03 D for the IOL Master and -0.23 D for the Galilei G6. The difference was not statistically significant (P = 0.059). The difference between the IOL power calculation of the IOL Master and the calculation of the G6 was not statistically significant (P = 0.064). The difference between the predicted refraction of the G6 and the refraction achieved after one month was also not statistically significant (P = 0.12) and neither was the difference between the predicted refraction of the IOL Master and the achieved refraction (P = 0.39). The mean axial length was calculated as 24.21 ± 0.80 mm using the IOL Master and 24.27 ± 0.82 mm using the Galilei G6 device. The mean value regarding anterior chamber depth (ACD) of the IOL master was 3.46 ± 0.23 mm and for the Galilei was G6 3.51 ± 0.25 mm. When comparing the white to white (WTW) values of the IOL master, it showed mean values of 12.32 ± 0.31 and Galilei showed mean values of G6 12.21 ± 0.28. All of these differences (between Galileo and IOL Master measurements) were statistically significant (P < 0.001).

Conclusion

Both the laser interferometry/keratometry performed by the IOL Master and the interferometry/raytracing biometry strategy performed by the Galilei G6 demonstrated equal results when executing the IOL power calculation before cataract surgery in eyes with no prior ocular surgery.

Quality of life in stable and progressive 'early-stage' keratoconus patients

PURPOSE

To analyse the vision-related quality of life (vr-QoL) in stable and progressive keratoconus (KC) patients with a still good visual acuity.

METHODS

Combined prospective/cross-sectional study design. The Refractive Status and Vision Profile (RSVP) and the National Eye Institute Visual Functioning - 25 (NEI-25) questionnaire were used in 16 emmetropic, 32 myopic and 56 KC patients, whereby KC patients with a stable (n = 26) and patients with a progressive stage (n = 30) and some of them before and after corneal cross-linking (CXL; n = 10) were included. All patients had a DCVA in at least one eye of ≥0.7 (decimal chart).

RESULTS

The analyses revealed a minor decline of the vr-QoL from emmetropes to myopes to early KC patients with a stable disease. Nonetheless, sociological subscales (i.e. 'social functioning', 'role difficulties' and 'dependency') did not display statistically significant differences comparing these groups. In progressive KC, we could demonstrate a statistically significant decline also of these sociological subscales, which did not improve after CXL.

CONCLUSION

Due to a still high and almost unaffected vr-QoL in early KC patients and the distinct decline after progression without rehabilitation after CXL, a reconsideration of current strategies to perform CXL only after a progression is diagnosed should be re-evaluated.

In vivo Histology of the Cornea - from the "Rostock Cornea Module" to the "Rostock Electronic Slit Lamp" - a Clinical "Proof of Concept" Study

INTRODUCTION

Confocal in vivo microscopy is an established method in ophthalmology research. As it requires contact coupling and calibration of the instruments is suboptimal, this method has been only rarely used in clinical routine work. As a result of close collaboration between physicists, information scientists and ophthalmologists, confocal laser scanning microscopy (CLSM) of the eye has been developed in recent years and a prototype can now be used in patients. The present study evaluates possible clinical uses of this method.

MATERIAL AND METHODS

The essential innovations in CLSM are (1) a newly designed coupling element with superficial adaptation to corneal curvature and (2) the use of a dual computerised piezo drive for rapid and precise focusing. In post-processing and after elastic imaging registration of the individual images parallel to the surface, it is also possible to produce sagittal sections resembling a split lamp and with resolution in the micrometer range. The concept was tested on enucleated pig bulbi and tested on normal volunteers and selected patients with diseases of the cornea.

RESULTS

Simultaneous imaging in planes parallel to the surface and in sagittal planes provided additional information that can help us to understand the processes of wound healing in all substructures of the cornea and the role of immune competent cells. Possible clinical uses were demonstrated in a volunteer with healthy eyes and several groups of patients (keratoconus after CXL, recurrent keratitis, status after PRK). These show that this new approach can be used in morphological studies at cellular level in any desired and appropriate test plane.

CONCLUSIONS

It could be shown that this new concept of CLSM can be used clinically. It can provide valuable and novel information to both preclinical researchers and to ophthalmologists interested in corneal disease, e.g. density of Langerhans cells and epithelial stratification in ocular surface diseases.

Analysis of excimer laser treatment outcomes and corresponding angle κ in hyperopic astigmatism

PURPOSE

To investigate the prevalence of preoperative, intraoperative, and postoperative angle κ in hyperopic eyes and its effect on the refractive outcomes of excimer laser vision correction.

SETTING

University Hospital Hamburg and Care Vision Refractive Centers, Germany.

DESIGN

Retrospective multicenter study.

METHODS

Hyperopic patients after laser in situ keratomileusis and before retreatment because of hyperopic regression were included. Three treatment groups were defined based on the magnitude of preoperative angle κ defined as low (<0.25 mm), moderate (0.25 to 0.50 mm), or high (>0.50 mm).

RESULTS

The study analyzed 170 hyperopic eyes of 112 patients (mean age 29.8 years ± 10.04 [SD], range 21 to 62 years). The preoperative angle κ was low, moderate, or high in 23, 49, and 98 cases, respectively. In eyes with a preoperative angle κ of 0.25 mm or more, changes in the x-axes and y-axes of angle κ and its magnitude were statistically significant (P < .05) between preoperative and intraoperative measurements. In these eyes, intraoperative angle κ (offset) was statistically significantly smaller (P < .05), and Purkinje images were statistically significantly more caudal (P < .001). Treatment predictability was independent from using preoperative or intraoperative angle κ, and there were no statistically significant differences in efficacy or safety.

CONCLUSIONS

A preoperative magnitude of angle κ as high as 0.50 mm or higher was present in more than 50% of regressed hyperopic eyes. Measuring angle κ preoperatively did not reflect its real-time intraoperative magnitude. Using the preoperatively larger angle κ as an intraoperative offset might result in a too nasally centered ablation that causes topographic and optical drawbacks; therefore, centering the ablation based on the intraoperative measured offset is recommended.

Whole-Exome Sequencing Identifies Novel Compound Heterozygous ZNF469 Mutations in Two Siblings with Mild Brittle Cornea Syndrome

Connective tissue diseases, including osteogenesis imperfecta (OI) and Ehlers-Danlos syndrome (EDS), exhibit a high degree of clinical and genetic heterogeneity. We report two sisters with blue sclerae, joint hypermobility and hearing loss. Whole-exome sequencing identified two compound heterozygous ZNF469 loss-of-function mutations due to a frameshift. Since these findings indicate the presence of brittle cornea syndrome (BCS), we performed ocular optical coherence tomography (OCT) and pachymetry, which revealed a moderate decrease in corneal thickness. While only one traumatic fracture was observed in each of the patients, a detailed skeletal assessment indicated no specific patterns of bone mass and microstructure reduction as well as normal bone turnover markers. Taken together, our findings point to a mild form of brittle cornea syndrome with a phenotype compatible with the extraskeletal features of OI but also with EDS.

Tomographic and Biomechanical Scheimpflug Imaging for Keratoconus Characterization: A Validation of Current Indices

PURPOSE

To analyze the potential benefit of the newly developed Tomography and Biomechanical Index (TBI) for early keratoconus screening.

METHODS

In this retrospective study, the discriminatory power of the corneal tomography Belin/Ambrósio Enhanced Ectasia Display (BAD-D) index and the newly developed Corvis Biomechanical Index (CBI) and TBI to differentiate between normal eyes, manifest keratoconus eyes (KCE), very asymmetric keratoconus eyes with ectasia (VAE-E), and their fellow eyes with either regular topography (VAE-NT) or regular topography and tomography (VAE-NTT) were analyzed by applying the t test (for normal distribution), Wilcoxon matched-pairs test (if not normally distributed), and receiver operating characteristic curve (ROC). The DeLong test was used to compare the area under the ROC (AUROC). Further, the cut-offs of the analyzed indices presented in a study by Ambrósio et al. from 2017 were applied in the study population to enable a cross-validation in an independent study population.

RESULTS

All indices demonstrated a high discriminative power when comparing normal and advanced keratoconus, which decreased when comparing normal and VAE-NT eyes and further when analyzing normal versus VAE-NTT eyes. The difference between the AUROCs reached a statistically significant level when comparing TBI versus BAD-D analyzing normal versus all included keratoconic eyes (P = .02). The TBI presented with the highest AUROCs throughout all conducted analyses when comparing different keratoconus stages, although not reaching a statistically significant level. Applying the cut-offs presented by Ambrósio et al. to differentiate between normal and VAE-NT in the study population, the accuracy was reproducible (accuracy in our study population with an optimized TBI cut-off: 0.72, with the cut-off defined by Ambrósio et al. 0.67).

CONCLUSIONS

The TBI enables karatoconus screening in topographical and tomographical regular keratoconic eyes. To further improve the screening accuray, prospective studies should be conducted. [J Refract Surg. 2018;34(12):840-847.].

Keratoconus Screening With Dynamic Biomechanical In Vivo Scheimpflug Analyses: A Proof-of-Concept Study

PURPOSE

This proof-of-concept study was designed to analyze the ability of in vivo biomechanical corneal analyses with the corneal visualization Scheimpflug technology (CorvisST; Oculus Optikgeräte, Wetzlar, Germany) to differentiate between normal eyes and eyes with manifest keratoconus after strictly eliminating the potential confounding factors intraocular pressure (IOP) and central corneal thickness (CCT).

METHODS

In this retrospective, cross-sectional study, after pairwise matching for CCT and IOP, 29 normal eyes and 29 keratoconic eyes (one eye from each patient) were selected as study population. Older CorvisST parameters and the new Corvis Biomechanical Index (CBI), including several biomechanical and one tomographic parameter, as well as an adjusted CBI (aCBI) (including only biomechanical parameters), were compared regarding their discriminative ability between both groups.

RESULTS

None of the CorvisST parameters of the former software version demonstrated statistically significant differences between normal and keratoconic eyes. On the other hand, the CBI and aCBI reached accuracies of 0.91 and 0.93, respectively, to discriminate between CCT- and IOP-matched normal and keratoconic eyes (CBI: [AUC/sensitivity/specificity]: 0.961/0.90/0.93; aCBI: [AUC/sensitivity/specificity]: 0.986/0.93/0.93).

CONCLUSIONS

This study demonstrated that the concept of keratoconus screening with the CorvisST is effective in differentiating keratoconic from non-keratoconic eyes. The next steps will be testing the indices in subclinical keratoconus cases and hopefully combining biomechanical analyses with already established topography and tomography indices to further improve current keratoconus screening. [J Refract Surg. 2017;33(11):773-778.].

Outcomes of retreatment after hyperopic laser in situ keratomileusis

PURPOSE

To evaluate the efficacy, predictability, and safety of laser in situ keratomileusis (LASIK) retreatment in eyes with hyperopia.

SETTING

Multicenter refractive surgery centers and University Hospital, Germany.

DESIGN

Retrospective case series.

METHODS

This multicenter study included hyperopic patients with a preoperative difference between cycloplegic and manifest refraction of 1.00 diopter (D) or less who had LASIK retreatment based on manifest refraction. The refractive outcome was analyzed according to standard graphs for reporting the efficacy, predictability, and safety of refractive surgery.

RESULTS

One hundred thirteen eyes of 113 consecutive hyperopic patients were enrolled. Efficacy (P < .001) and safety (P = .004) were statistically significantly improved by retreatment without being negatively influenced by preoperative manifest spherical equivalent (SE), manifest cylinder, or keratometry. In cases still showing a trend toward undercorrection, retreatment resulted in 88 eyes (78.0%) being within ±0.50 D of the attempted correction. The optical zone (OZ) diameter of the retreatment did not correlate with efficacy, predictability, or safety.

CONCLUSIONS

Retreatment after hyperopic LASIK resulted in high efficacy, predictability, and safety outcomes. The efficacy and safety of the retreatment were not affected by preoperative manifest SE, manifest cylinder, keratometry, or OZ diameter.

Endothelial Cell Count in Eye Bank Corneal Grafts: Impact of Death Cause and Donor Diseases

PURPOSE

The purpose of this study is to analyze the impact of death causes and documented donor diseases on initial endothelial cell counts (after retrieval) and the development of corneal graft endothelia during organ culture.

METHODS

The retrospective statistic analyses was conducted on a data set of 10,185 human corneas prepared at the Hamburg Eye Bank.

RESULTS

Although we observed that death by gunshot trauma or alcoholism seems to be associated with marginally higher endothelium cell counts (independently from donor age), we could prove that only donor age is a relevant predictive parameter for the initial cell-density of the endothelium and its development in vitro.

CONCLUSION

We conclude that an extension of prospective quality parameters for donor selection additional to donor age (such as individual causes of death) is not necessary.

[Multifocal intraocular lens (MIOL) surgery in young non-presbyopic ametropes : Reasonable and safe?]

BACKGROUND

Refractive lens exchange and implantation of a multifocal intraocular lens (MIOL) is mainly advised for ametropes with presbyopia. Non-presbyopic young ametropes who wish spectacle-independence are usually treated with corneal refractive surgery or phakic lenses.

OBJECTIVES

This retrospective case series aimed to analyse the refractive and subjective satisfaction outcome after MIOL surgery in both eyes of non-presbyopic ametropes where other treatment options were not possible.

MATERIALS AND METHODS

This retrospective case series comprised consecutively treated 32 eyes of 16 patients (5 myopic, 11 hyperopic patients; mean age 31 ± 6 years) who wished spectacle-independence and thus received an aspheric bifocal biconvex refractive-diffractive single-piece MIOL (Acri.Lisa 366/809, Carl Zeiss Meditec AG). Refractive data prior to and after surgery as well as subjective satisfaction at the 1‑year follow-up examination were assessed.

RESULTS

Related to distance corrected near visual acuity myopic eyes had a median efficacy index (EI) of 0.92 (±0.20) and hyperopes of 0.91 (±0.12) (P = 0.415). For intermediate vision, in both groups a lower EI (<0.5; P = 0.188) resulted in lower subjective satisfaction, which was higher for near and distance vision. Some of hyperopic patients reported limitations in near and distance vision, only one hyperopic patient would not have chosen this surgery again. None had a related complication during the follow-up.

CONCLUSIONS

When neither laser refractive surgery nor implantation of a phakic lens is possible, young non-presbyopic ametropes do profit from MIOL surgery with an aspheric bifocal biconvex refractive-diffractive MIOL.

The role of the multidisciplinary health care team in the management of patients with Marfan syndrome

Marfan syndrome (MFS) is a rare, severe, chronic, life-threatening disease with multiorgan involvement that requires optimal multidisciplinary care to normalize both prognosis and quality of life. In this article, each key team member of all the medical disciplines of a multidisciplinary health care team at the Hamburg Marfan center gives a personal account of his or her contribution in the management of patients with MFS. The authors show how, with the support of health care managers, key team members organize themselves in an organizational structure to create a common meaning, to maximize therapeutic success for patients with MFS. First, we show how the initiative and collaboration of patient representatives, scientists, and physicians resulted in the foundation of Marfan centers, initially in the US and later in Germany, and how and why such centers evolved over time. Then, we elucidate the three main structural elements; a team of coordinators, core disciplines, and auxiliary disciplines of health care. Moreover, we explain how a multidisciplinary health care team integrates into many other health care structures of a university medical center, including external quality assurance; quality management system; clinical risk management; center for rare diseases; aorta center; health care teams for pregnancy, for neonates, and for rehabilitation; and in structures for patient centeredness. We provide accounts of medical goals and standards for each core discipline, including pediatricians, pediatric cardiologists, cardiologists, human geneticists, heart surgeons, vascular surgeons, vascular interventionists, orthopedic surgeons, ophthalmologists, and nurses; and of auxiliary disciplines including forensic pathologists, radiologists, rhythmologists, pulmonologists, sleep specialists, orthodontists, dentists, neurologists, obstetric surgeons, psychiatrist/psychologist, and rehabilitation specialists. We conclude that a multidisciplinary health care team is a means to maximize therapeutic success.

New Scheimpflug Dynamic In Vivo Curve Analyses to Characterize Biomechanical Changes of the Cornea After Cross-linking for Progressive Keratoconus

PURPOSE

To evaluate the effect of corneal cross-linking (CXL) in progressive keratoconus by applying in vivo static and dynamic Scheimpflug analyses.

METHODS

In this longitudinal retrospective study, corneal topography and tomography (Pentacam HD) and dynamic Scheimpflug-based biomechanical analyses (CorvisST [CST]) of 24 eyes of 24 patients with progressive keratoconus before and 6 months after CXL were reviewed. New dynamic curve analyses, provided by Oculus Optikgeräte, were performed to analyze corneal dynamics throughout the entire response to the CST air puff impulse.

RESULTS

Besides subtle changes of topography and tomography, only the CorvisST predefined parameters peak distance (-0.5 mm) and radius of the intended cornea (+0.5 mm; P < .05) demonstrated statistically significant differences 6 months after CXL. Using new dynamic curve analyses, additional distinct changes of the corneal biomechanical characteristics after CXL were noted.

CONCLUSIONS

Published results of corneal biomechanical changes after CXL for progressive keratoconus based on single, predefined CST parameters are inconsistent. The new dynamic curve analyses demonstrate distinct changes of the biomechanical properties of the cornea and might therefore be the next step in understanding in vivo analyses of corneal biomechanics.

Pseudolentogenic astigmatic effect of multifocal intraocular lenses: non-corneal ocular residual astigmatism (N-CORA) as a new parameter in astigmatic change analysis

PURPOSE

This study was initiated to introduce the term non-corneal ocular residual astigmatism (N-CORA) as a new parameter in astigmatic change analysis after implantation of two different types of non-toric, multifocal intraocular lenses (MIOL).

METHODS

Seventy-two eyes from 72 consecutive patients after MIOL surgery were studied in terms of a retrospective, cross-sectional data analysis. Two types of spherical MIOL were used. Surgical technique in all patients was a 2.4-mm incision phacoemulsification, performed by one surgeon. To investigate the magnitude and axis of astigmatic changes, the true corneal astigmatism and Alpins vector method were applied.

RESULTS

There were no statistically significant between-group differences related to the preoperative refraction or ocular residual astigmatism (ORA). After surgery, the mean refractive surgically induced astigmatism (RSIA) and the topographic SIA (TSIA) did not differ significantly between the lenses. The magnitude and orientation of ORA and N-CORA changed after surgery.

CONCLUSIONS

There are no statistically significant differences in postoperative ORA in magnitude or axis when implanting different types of MIOL. The similarity of N-CORA between both MIOL types shows that both diffractive and refractive asymmetric MIOLs with plate haptics have the same pseudolentogenic astigmatic effect which could be presented in terms of the newly introduced parameter N-CORA.

Ocular residual astigmatism (ORA) in pre-cataract eyes prior to and after refractive lens exchange

The purpose of this study was to analyze ocular residual astigmatism (ORA) before and after implantation of two different optical types of non-toric multifocal intraocular lenses (MIOL) in pre-cataract patients. This retrospective cohort study analyzed 72 eyes from 72 consecutive patients after MIOL surgery . To investigate magnitude and axis of astigmatic changes, the concepts of true corneal astigmatism and Alpins vector method were applied. There were no statistically significant between-group differences prior to surgery. The mean refractive surgically induced astigmatism (RSIA) (P = 0.063) and the topographic SIA (TSIA) (P = 0.828) did not differ significantly between the lenses, and the summated vector mean for ORA was reduced in terms of magnitude by approximately 0.30 Diopter. ORA in pseudophakic eyes mainly results from the posterior corneal surface and less from IOL tilting, postoperative posterior capsule shrinkage, or secondary cataract.

[Unilateral Solar Maculopathy after Gazing at Solar Eclipse]

A 43-year-old male patient with unilateral metamorphosia presented after gazing at an eclipse with only one eye. Damage of the macula was demonstrated funduscopically, with OCT and angiography. Six weeks after initial presentation and oral methylprednisolone therapy (40 mg/d for 10 days), the symptoms and the morphological changes decreased. Solar retinopathy is a photochemical alteration of the retina, usually seen after sun gazing. In younger patients, it mostly presents as bilateral solar maculopathy. Some patients exhibit partial or total recovery.

Role of preoperative cycloplegic refraction in LASIK treatment of hyperopia

BACKGROUND

Previous studies have suggested that, to improve refractive predictability in hyperopic LASIK treatments, preoperative cycloplegic or manifest refraction, or a combination of both, could be used in the laser nomogram. We set out to investigate (1) the prevalence of a high difference between manifest and cycloplegic spherical equivalent in hyperopic eyes preoperatively, and (2) the related predictability of postoperative keratometry.

METHODS

Retrospective cross-sectional data analysis of consecutive treated 186 eyes from 186 consecutive hyperopic patients (mean age 42 [±12] years) were analyzed. Excimer ablation for all eyes was performed using a mechanical microkeratome (SBK, Moria, France) and an Allegretto excimer laser platform. Two groups were defined according to the difference between manifest and cycloplegic spherical equivalent which was defined as ≥1.00 diopter (D); the data was analyzed according to refractive outcome in terms of refractive predictability, efficacy, and safety.

RESULTS

In 24 eyes (13 %), a preoperative difference of ≥1.00D between manifest spherical equivalent and cycloplegic spherical equivalent (= MCD) occurred. With increasing preoperative MCD, the postoperative achieved spherical equivalent showed hyperopic regression after 3 months. There was no statistically significant effect of age (accommodation) or optical zone size on the achieved spherical equivalent.

CONCLUSIONS

A difference of ≥1.00D occurs in about 13 % of hyperopia cases. We suggest that hyperopic correction should be based on the manifest spherical equivalent in eyes with preoperative MCD <1.00D. If the preoperative MCD is ≥1.00D, treatment may produce manifest undercorrection, and therefore we advise that the patient should be warrned about lower predictability, and suggest basing conclusions on the arithmetic mean calculated from the preoperative manifest and cycloplegic spheres.

Flap-induced astigmatism in eyes with sphere myopia correction: Superior hinge using a rotating microkeratome versus nasal hinge using a linear microkeratome

PURPOSE

To compare the effect of a rotating microkeratome (M2) and a linear microkeratome (SBK) on the change in the astigmatic component in eyes with preoperative plano refractive cylinder.

SETTING

University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.

DESIGN

Retrospective case series.

METHODS

An Allegretto excimer laser was used to perform laser ablation in myopic eyes of consecutive patients. The laser in situ keratomileusis (LASIK) procedure included mechanical flap preparation using a microkeratome, either a linear type with a single-use 90 μm head to create a nasal hinge or a rotating type with a single-use 90 μm head to create a superior hinge. The Alpins vector method was applied to describe the effects of LASIK on postoperative refractive cylinder.

RESULTS

The study evaluated 1045 eyes of 852 patients. Although the mean overall efficacy and safety indices indicate the procedure was highly precise, safe, and efficient, there were statistically significant differences in surgically induced astigmatism (SIA) between the microkeratomes (P = .002). The postoperative refractive cylinder (ie, SIA) was 0.75 diopter (D) or more in 116 eyes (11.1%), 44 (12.8%) of 344 linear cases and 72 (10.3%) of 701 rotating cases. Independent of the type of microkeratome used, the SIA was slightly higher in eyes treated first; the mean magnitude of the induced astigmatism was 0.35 D.

CONCLUSIONS

In approximately 10% of eyes with preoperative plano refractive myopia, the astigmatic component tended to be overcorrected. Nevertheless, independent of the type of microkeratome, the maximum mean magnitude of refractive cylinder documented was 0.35 D.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Correlation of the KISA% index and Scheimpflug tomography in 'normal', 'subclinical', 'keratoconus-suspect' and 'clinically manifest' keratoconus eyes

PURPOSE

To analyse tomographic changes in eyes classified as 'normal', 'keratoconus-suspect' and 'clinically manifest keratoconus' based on the established KISA% definition of Rabinowitz and Rasheed and to develop the category of 'subclinical keratoconus eyes' to expand the classification into a 'subtopographic' range.

METHODS

Tomographic and topographic analyses of 670 eyes performed with a rotating Scheimpflug imaging system (Pentacam(®), Oculus Inc., Wetzlar, Germany) were retrospectively analysed. Based on the KISA% keratoconus classification system, eyes were assigned to a 'normal', 'keratoconus-suspect' or 'manifest keratoconus' group. In addition, a new group of 'subclinical keratoconus eyes' was analysed, comprising unsuspicious fellow eyes of patients with keratoconus. T-tests, Wilcoxon rank-sum test, receiver operating characteristics (ROC) and robust regression analyses were performed to correlate tomographic parameters with the increasing KISA% index.

RESULTS

KISA%-grouped keratoconus eyes showed robust tomographic changes. By adding the subclinical group, although the concurrent topography was unchanged, we were able to demonstrate statistically significant changes for almost all tomographic parameters (parameters with highest sensitivity/specificity: ART_max, [0.69/0.69], BAD_D [0.66/0.66]). The highest coefficient of determination (R(2)) with the KISA% index was demonstrated for Ele_f_max (R(2) = 0.70), Ele_f_TP (R(2) = 0.69), Ele_b_TP (R(2) = 0.69) and BAD_D (R(2) = 0.68).

CONCLUSION

We recommend the use of the expanded KISA% index (eKISA% index) as the basis for the definition of keratoconus and normal groups in future keratoconus research projects.

LASIK for spherical refractive myopia: effect of topographic astigmatism (ocular residual astigmatism, ORA) on refractive outcome

Purpose

In eyes with a preoperative plano refractive cylinder, it would appear that there is no rationale for astigmatic treatment. The aim of this retrospective, cross-sectional data analysis was to determine the amount of topographic astigmatism in refractive plano eyes that results in reduced efficacy after myopic laser in situ keratomileusis (LASIK).

Methods

This study included 267 eyes from 267 consecutive myopic patients with a refractive plano cylinder. Receiver operating characteristic analysis was used to find the cut-off values of preoperative ocular residual astigmatism (= topographic astigmatism) that can best discriminate between groups of efficacy and safety indices in preoperative plano refractive cylinder eyes.

Results

Preoperative ocular residual astigmatism (ORA) (or topographic astigmatism) of ≤0.9 diopters (D) resulted in an efficacy index of at least 0.8 statistically significantly more frequently than eyes with a preoperative ORA of >0.9 D. Eyes with a high ORA preoperatively also had a high ORA postoperatively. Regression analysis showed that each diopter of preoperative ORA reduced efficacy by 0.07.

Conclusion

A preoperative corneal astigmatism of ≥0.9 D could (partially) be taken into account in the LASIK design, even if the subjective refractive astigmatism is neutral.

[Perspectives of laser-assisted keratoplasty: current overview and first preliminary results with the picosecond infrared laser (λ = 3 µm)]

BACKGROUND

This article provides a review of the current state of laser-assisted keratoplasty and describes a first proof of concept study to test the feasibility of a new mid-infrared (MIR) picosecond laser to perform applanation-free corneal trephination.

METHODS

The procedure is based on a specially adapted laser system (PIRL-HP2-1064 OPA-3000, Attodyne, Canada) which works with a wavelength of 3,000 ± 90 nm, a pulse duration of 300 ps and a repetition rate of 1 kHz. The picosecond infrared laser (PIRL) beam is delivered to the sample by a custom-made optics system with an implemented scanning mechanism. Corneal specimens were mounted on an artificial anterior chamber and subsequent trephination was performed with the PIRL under stable intraocular pressure conditions.

RESULTS

A defined corneal ablation pattern, e.g. circular, linear, rectangular or disc-shaped, can be selected and its specific dimensions are defined by the user. Circular and linear ablation patterns were employed for the incisions in this study. Linear and circular penetrating PIRL incisions were examined by macroscopic inspection, histology, confocal microscopy and environmental scanning electron microscopy (ESEM) for characterization of the incisional quality. Using PIRL reproducible and stable incisions could be made in human and porcine corneal samples with minimal damage to the surrounding tissue.

CONCLUSION

The PIRL laser radiation in the mid-infrared spectrum with a wavelength of 3 µm is exactly tuned to one of the dominant vibrational excitation bands of the water molecule, serves as an effective tool for applanation-free corneal incision and might broaden the armamentarium of corneal transplant surgery.

Effects of laser in situ keratomileusis (LASIK) on corneal biomechanical measurements with the Corvis ST tonometer

Purpose

This study was initiated to evaluate biomechanical changes using the Corvis ST tonometer (CST) on the cornea after laser in situ keratomileusis (LASIK).

Setting

University Medical Center Hamburg-Eppendorf, Germany, and Care Vision Refractive Centers, Germany.

Design

Retrospective cohort study.

Methods

This retrospective study included 37 eyes of 37 refractive patients. All CST measurements were performed 1 day before surgery and at the 1-month follow-up examination. The LASIK procedure included mechanical flap preparation using a Moria SBK microkeratome and an Allegretto excimer laser platform.

Results

Statistically significant differences were observed for mean first applanation length, mean first and second deflection lengths, mean first and second deflection amplitudes, radius of curvature, and peak distance. Significant positive correlations were found between the change (Δ) of radius of curvature and manifest refraction spherical equivalent (MRSE), ablation depth, and Δintraocular pressure as well as between AD and ΔHC-time. Each diopter of myopic correction in MRSE resulted in an increase in Δradius of curvature of 0.2 mm.

Conclusion

Several CST parameters were statistically significantly altered by LASIK, thereby indicating that flap creation, ablation, or both, significantly change the ability of the cornea to absorb or dissipate energy.

Postoperative refractive error after phacovitrectomy for epiretinal membrane with and without macular oedema

PURPOSE

This study was initiated to investigate whether the presence of macular oedema influenced intraocular lens (IOL) power calculation in eyes with epiretinal membrane.

METHODS

The files of patients undergoing combined phacoemulsification were retrospectively reviewed. Two groups were defined according to presence of macular oedema. The main outcome measure was the IOL power prediction error (PE). Secondary outcome measures were the correlation between preoperative macular thickness, absolute change of macular thickness and dioptric shift. The mean postoperative PE achieved with the Haigis formula was compared with the PE that would have been obtained had the SRKII and HofferQ formulas been used.

RESULTS

We investigated 47 eyes of 47 consecutive patients. Regardless of the IOL formula used, the PE was on average higher in eyes without macula oedema (group 1). The myopic dioptric shift was dependent on preoperative macular thickness and absolute change of macular thickness. This association was more markedly pronounced in group 1.

CONCLUSIONS

Increased retinal thickness is the main cause for underestimation of the cornea-photoreceptor layer distance, and therefore could contribute to inaccuracy in IOL power calculations. The current results show that a myopic shift tends to be less pronounced in cases where a macula oedema is present. Eyes with pure traction have less predictable refractive results in terms of higher PE and dioptric shift.

First clinicial results on the feasibility, quality and reproducibility of aberrometry-based intraoperative refraction during cataract surgery

OBJECTIVE

To provide the first clinical data in determining the feasibility, quality and precision of intraoperative wavefront aberrometry (IWA)-based refraction in patients with cataract.

DESIGN

IWA refraction was recorded at 7 defined measurement points during standardised cataract surgery in 74 eyes of 74 consecutive patients (mean age 69±11.3 years). Precision and measurement quality was evaluated by the 'limits of agreement' approach, regression analysis, correlation analysis, Analysis of variance (ANOVA) and ORs for predicting measurement failure. Wavefront map (WFM) quality was objectivised and compared with the Pentacam Nuclear Staging analysis.

RESULTS

Out of 814 IWA measurement attempts, 462 WFMs could be obtained. The most successful readings (n=63) were achieved in aphakia with viscoelastic. The highest (50.63%, SD 20.23) and lowest (29.19%, SD 13.94) quality of WFMs across all measurement points were found after clear corneal incision and in pseudophakia with viscoelastic, respectively. High consistency across repeated measures were found for mean spherical equivalent (SE) differences in aphakia with -0.01D and pseudophakia with -0.01D, but ranges were high (limits of agreement +0.69 D and -0.72 D; +1.53 D and -1.54 D, respectively). With increasing WFM quality, higher precision in measurements was observed.

CONCLUSIONS

This is the first report addressing quality and reproducibility of WA in a large sample. IWA refraction in aphakia, for instance, appears to be reliable once stable and pressurised anterior chamber conditions are achieved. More efforts are required to improve the precision and quality of measurements before IWA can be used to guide the surgical refractive plan in cataract surgery.

Laser in situ keratomileusis for astigmatism ≤ 0.75 diopter combined with low myopia: a retrospective data analysis

Background

This study examined the refractive and visual outcome of wavefront-optimized laser in situ keratomileusis (LASIK) in eyes with low myopia and compound myopic astigmatism ≤ 0.75 diopter (D).

Methods

153 eyes from 153 consecutive myopic patients (74 male, 79 female; mean age at surgery 40.4 ± 10.4 years) who had a preoperative refractive cylinder ≤ 0.75 D and a manifest sphere between -0.25 D and -2.75 D, and who had completed 4-month follow-up. Three subgroups defined by the magnitude of preoperative manifest refractive cylinder (0.25, 0.50, and 0.75 D) were formed. Manifest refraction, uncorrected and corrected visual acuity were assessed pre- and postoperatively. The astigmatic changes achieved were determined using the Alpins vector analysis.

Results

After 4 months (120.0 ± 27.6 days) of follow-up, a mean uncorrected distant visual acuity of 0.07 ± 0.11 logMAR and a mean manifest refraction spherical equivalent of -0.06 ± 0.56 D were found. There was no statistically significant difference in efficacy and safety between the preoperative cylinder groups. Astigmatic overcorrection for preoperative cylinder of ≤ 0.50 D was suggested by the correction index, the magnitude of error, the index of success, and the flattening index.

Conclusions

Low myopic eyes with a preoperative cylinder of ≤ 0.50 D were significantly overcorrected with regard to cylinder correction when combined with low myopic LASIK. Accordingly, we are cautious in recommending full astigmatic correction for eyes with low myopia and manifest cylinder of ≤ 0.50 D.

Ocular residual astigmatism: effects of demographic and ocular parameters in myopic laser in situ keratomileusis

PURPOSE

To analyze the influence of demographic and ocular factors on ocular residual astigmatism (ORA) in myopic laser in situ keratomileusis (LASIK).

SETTING

University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

DESIGN

Retrospective cross-sectional data analysis.

METHODS

Eyes of consecutive myopic patients scheduled for LASIK were studied to evaluate the influence on preexisting ORA of age, sex, ocular dominance, subjective cylinder and topographic astigmatism, subjective sphere, and mesopic pupil size. The ORA was determined using Alpins vector analysis. Two subgroups, defined by the ratio of ORA to preoperative refractive cylinder (R), were formed: ORA:R ≥ 1.0 and ORA:R <1.0).

RESULTS

The study comprised 2991 eyes (2991 patients). The mean ORA was 0.75 diopter (D) ± 0.39 (SD) (range 0.00 to 2.00 D); 1372 (46%) eyes had ORA of 1.00 D or more. Ordinary least square estimations and odds ratios showed that subjective sphere, male sex, and dominant eye were negative predictors of the degree of preoperative ORA, while increasing age and larger mesopic pupils did not indicate ORA orientation. With-the-rule astigmatism meridian was more likely in eyes with low ORA, while oblique and against-the-rule meridians were related to high ORA.

CONCLUSIONS

The preoperative assessment of refractive surgery candidates should consider the interaction between topographic, refractive, and ORA because corneal refractive surgery is more successful in eyes in which the cylinder mainly originates from the anterior cornea. The current data can help identify patients at high risk for having a significant difference between subjective cylinder and topographic astigmatism.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Nonneuronal control of the differential distribution of myelin along retinal ganglion cell axons in the mouse

PURPOSE

In most mammalian species, retinal ganglion cell (RGC) axons are myelinated in the optic nerve, but remain nonmyelinated in the retinal nerve fiber layer and the most proximal (i.e., retina-near) region of the nerve. Here we analyzed whether RGCs are involved in the control of this characteristic distribution of oligodendrocytes and myelin in the primary visual pathway of mice.

METHODS

Neurospheres were enriched in oligodendrocyte progenitor cells (OPCs) by a short-term exposure to platelet-derived growth factor (PDGF) and grafted into the retina of young postnatal mice close to the optic disc. Immunohistochemistry was performed to study the integration and differentiation of the grafted cells, and the formation of donor-derived myelin in the normally nonmyelinated retinal nerve fiber layer and intrabulbar and most proximal retrobulbar region of the optic nerve.

RESULTS

Intraretinal transplantations of small-sized PDGF-treated neurospheres into young postnatal mice resulted in extensive integration of the grafted cells into host retinas. A significant fraction of the donor cells differentiated into oligodendrocytes that myelinated the nerve fiber layer. Importantly, RGC axon segments within the normally nonmyelinated intrabulbar and most proximal retrobulbar region of the nerve also became myelinated in a fraction of animals.

CONCLUSIONS

This is the first report demonstrating that the normally nonmyelinated intrabulbar and retrobulbar segments of RGC axons are competent to become myelinated. Results support the view that the differential distribution of myelin and oligodendrocytes in the primary visual pathway is controlled by nonneuronal factors rather than by the RGCs themselves.

Thirty years of cornea cultivation: long-term experience in a single eye bank

PURPOSE

To evaluate donor demographics, trends in donor tissue procurement and tissue storage over a long period.

METHODS

A retrospective, longitudinal, descriptive analysis was undertaken of data from the Hamburg Eye Bank Data Base (HEB-DB) that had been collected between 1981 and 2010. Data on 54 parameters of cornea donors [including clinical history, age, death cause, gender and death-to-explantation interval (DEI)] and of cultivated corneas (endothelial quality and development in culture, cultivation period, microbiological contamination) were retrieved. These data were analysed statistically, focusing on the historical development of the eye bank.

RESULTS

At the time of retrieval (June 2010), the HEB-DB contained data on 10 943 corneas (5503 donors). Most donors were men (65%) and had died from cardiopulmonary (n = 801)/cerebral (n = 261) failure or as the result of a polytraumatic accident/suicide (n = 602). Within these years, donor age, DEI and storage time increased. The percentage of stored corneas suitable for transplantation displayed a variable but increasing trend; in 2007, almost 75% of the stored corneas were transplanted. Between 1995 and June 2010, the median microbiological contamination rate was 5.3%. A change in the procurement procedure from enucleation to corneoscleral explantation in 2008 led to a briefly increased contamination rate.

CONCLUSION

  Donor demographic data run parallel to the general demographic development. Our analysis indicates a dynamic development of the eye bank over the last 30 years and emphasizes the need for an active quality management in coping with the challenges of modern eye banking.

[Difference and distance between the central and thinnest points of the cornea: impact of refractive state, age and ocular side]

BACKGROUND

The aim of the study was to quantify the difference in corneal thickness between the central and thinnest points (∆PachyZ-PachyD), the distance between the center of the cornea and its thinnest point (vector length PachyD) and to explore the impact of refractive state, age and ocular side.

PATIENTS AND METHODS

This was a multicenter, retrospective, cross-sectional study and medical records of 16,872 eyes were reviewed. The Orbscan® (Bausch and Lomb) procedure was used for pachymetry and keratometry.

RESULTS

The results showed that ∆PachyZ-PachyD and vector length PachyD were higher in hyperopic eyes (∆PachyZ-PachyD: 11.99 ± 12.08 µm, vector length PachyD: 0.85 ± 0.44 mm) compared to myopic eyes (∆PachyZ-PachyD: 9.2 ± 7.86 µm, vector length PachyD: 0.7 ± 0.37 mm; p < 0.001). Refractive state, age and ocular side demonstrated an independent, statistically significant impact on ∆PachyZ-PachyD and vector length PachyD.

CONCLUSIONS

As a result of the significant impact of refractive state, age and ocular side on ∆PachyZ-PachyD and vector length PachyD, these variables should be considered in a normative data collection.

Eye laterality: a comprehensive analysis in refractive surgery candidates

PURPOSE

To explore eye laterality (higher refractive error in one eye) and its association with refractive state, spherical/astigmatic anisometropia, age and sex in refractive surgery candidates.

METHODS

Medical records of 12 493 consecutive refractive surgery candidates were filtered. Refractive error (subjective and cycloplegic) was measured in each subject and correlated with eye laterality. Only subjects with corrected distance visual acuity (CDVA) of >20/22 in each eye were enrolled to exclude amblyopia. Associations between eye laterality and refractive state were analysed by means of t-test, chi-squared test, Spearman's correlation and multivariate logistic regression analysis, respectively.

RESULTS

There was no statistically significant difference in spherical equivalent between right (-3.47 ± 2.76 D) and left eyes (-3.47 ± 2.76 D, p = 0.510; Pearson's r = 0.948, p < 0.001). Subgroup analysis revealed (I) right eye laterality for anisometropia >2.5 D in myopic (-5.64 ± 2.5 D versus -4.92 ± 2.6 D; p = 0.001) and in hyperopic (4.44 ± 1.69 D versus 3.04 ± 1.79 D; p = 0.025) subjects, (II) a tendency for left eye cylindrical laterality in myopic subjects, and (III) myopic male subjects had a higher prevalence of left eye laterality. (IV) Age did not show any significant impact on laterality.

CONCLUSIONS

Over the full refractive spectrum, this study confirmed previously described strong interocular refractive correlation but revealed a statistically significant higher rate of right eye laterality for anisometropia >2.5 D. In general, our results support the use of data from one eye only in studies of ocular refraction.

[Therapeutic excimer laser treatment of the cornea]

Concomitant with new innovations in the field of refractive surgery, therapeutic excimer laser applications like phototherapeutic keratectomy (PTK) and topography-guided customised ablation treatment are gaining high importance and undergoing rapid evolution. Nowadays, PTK is an effective treatment modality for superficial corneal pathologies. Primary indications are decreased epithelial adherence, superficial opacifications and an irregular corneal surface. For the right indication and successful treatment of corneal pathologies with PTK, a knowledge of the size, depth and nature of the pathology, as well as the refractive status of both eyes is important. Next to slit-lamp examination, objective measuring systems like the topography, confocal microscopy and the anterior segment OCT facilitate presurgical planning. Regarding the treatment procedure the surgeon can choose between a variety of methods. PTK can be combined with manual epithelial debridement or done by only using the excimer laser. In the case of an irregular corneal surface, depending on the pathology, masking fluids or topography-guided custom ablation protocols can increase the visual outcome. To avoid recurrence of the underlying pathology (e.g., corneal dystrophy, haze), the topical application of 0.02% mitomycin C for 20-60 seconds has proved to be a safe and effective procedure. If the surgeon considers all the patient-related factors carefully and manages to combine the available treatment options correctly, PTK embodies an effective and minimally invasive alternative to lamellar or penetrating keratoplasty.

Association between ocular dominance and spherical/astigmatic anisometropia, age, and sex: analysis of 1274 hyperopic individuals

PURPOSE

To determine the association between ocular dominance and spherical/astigmatic anisometropia, age, and sex in hyperopic subjects.

METHODS

The medical records of 1274 hyperopic refractive surgery candidates were filtered. Ocular dominance was assessed with the hole-in-the-card test. Refractive error (manifest and cycloplegic) was measured in each subject and correlated to ocular dominance. Only subjects with corrected distance visual acuity of >20/22 in each eye were enrolled, to exclude amblyopia. Associations between ocular dominance and refractive state were analyzed by means of t-test, χ(2) test, Spearman correlation, and multivariate logistic regression analysis.

RESULTS

Right and left eye ocular dominance was noted in 57.4 and 40.5% of the individuals. Nondominant eyes were more hyperopic (2.6 ± 1.27 diopters [D] vs. 2.35 ± 1.16 D; P < 0.001) and more astigmatic (-1.3 ± 1.3 D vs. -1.2 ± 1.2 D; P = 0.003) compared to dominant eyes. For spherical equivalent (SE) anisometropia of >2.5 D (n = 21), the nondominant eye was more hyperopic in 95.2% (SE 4.7 ± 1.4 D) compared to 4.8% (1.8 ± 0.94 D; P < 0.001) for the dominant eye being more hyperopic. For astigmatic anisometropia of >2.5 D (n = 27), the nondominant eye was more astigmatic in 89% (mean astigmatism -3.8 ± 1.1 D) compared to 11.1% (-1.4 ± 1.4 D; P < 0.001) for the dominant eye being more astigmatic.

CONCLUSIONS

The present study is the first to show that the nondominant eye has a greater degree of hyperopia and astigmatism than the dominant eye in hyperopic subjects. The prevalence of the nondominant eye being more hyperopic and more astigmatic increases with increasing anisometropia.

Association between ocular dominance and spherical/astigmatic anisometropia, age, and sex: analysis of 10,264 myopic individuals

PURPOSE

To determine the association between ocular dominance and spherical or astigmatic anisometropia, age, and sex.

METHODS

Medical records of 10,264 myopic refractive surgery candidates were filtered. Ocular dominance was assessed with the hole-in-the-card test. Manifest refractive error was measured in each subject and correlated to ocular dominance. Only subjects with corrected distance visual acuity (CDVA) of >20/22 in each eye were enrolled, to exclude amblyopia. Associations between ocular dominance and refractive state were analyzed by means of the t-test, χ(2) test, Spearman correlation, and multivariate logistic regression analysis.

RESULTS

Right and left eye ocular dominance was noted in 61.7% and 35.6% of the individuals. Ocular dominance had no significant impact on SE refraction in subjects with SE or cylindrical anisometropia <0.5 D. For anisometropia >2.5 D (n = 278) the nondominant eye was more myopic in 63.7% (SE -5.8 ± 2.64 D) compared to 36.3% (-4.69 ± 2.39 D; P < 0.001; adjusted P (Padj) < 0.001) for the dominant eye being more myopic. Nondominant eyes showed higher astigmatic power than dominant eyes (-0.95 ± 0.91 D versus -0.89 ± 0.84 D; P < 0.001). For astigmatic anisometropia >2.5 D, nondominant eyes exhibited a higher amount of astigmatism in 75% of subjects. Nondominant eyes of subjects <29 years and 30 to 39 years of age had a significantly higher astigmatic power than did dominant eyes of the same age group.

CONCLUSIONS

In contrast to previous reports, this study, including myopic refractive surgery candidates, revealed that the nondominant eye was more myopic for SE anisometropia >2.5 and more astigmatic for cylindrical anisometropia >0.5 D.

Relationship between minimum corneal thickness and refractive state, keratometry, age, sex, and left or right eye in refractive surgery candidates

PURPOSE

To evaluate the relationship between the thinnest point in corneal thickness and the refractive state, keratometry, age, sex, and the ocular side.

SETTING

Eye clinics in Germany and Austria and the Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

DESIGN

Cross-sectional study.

METHODS

Medical records of refractive surgery candidates from 2006 to 2010 were reviewed. Univariate variance analysis, covariance analysis, Bravis-Pearson correlations, Spearman rank correlations, and t tests were performed to analyze the relationship between the thinnest point in corneal thickness and the biometric parameters.

RESULTS

The study evaluated 4600 eyes. The mean thinnest point in corneal thickness was 549 μm ± 33 (SD). Refractive state, mean keratometry, and age had a statistically significant impact on the thinnest point in corneal thickness. The mean thinnest point in corneal thickness was 548 ± 33 μm in myopia, 555 ± 34 μm in hyperopia, and 553 ± 35 μm in high astigmatism, with a statistically significant difference between hyperopic eyes and myopic eyes (P<.001). No correlation was found between the thinnest point in corneal thickness and sex or ocular side. Refractive state (r = 0.07, P<.001) and age (r = 0.05, P<.001) showed a positive correlation and keratometry (r = -0.09, P<.001) a negative correlation with the thinnest point in corneal thickness.

CONCLUSIONS

Refractive state, mean keratometry, and age had a statistically significant, although marginal impact, on the thinnest point in corneal thickness. Sex and the ocular side had no effect.

Bilateral crystalline corneal deposits as first clinical manifestation of monoclonal gammopathy: a case report

Aims

To report the clinical and diagnostic findings of a patient with bilateral corneal deposits caused by an underlying monoclonal gammopathy.

Methods

Slit-lamp biomicroscopy, confocal microscopy and additional serological tests were performed on a 35-year-old man presenting with bilateral crystalline corneal deposits.

Results

The patient was diagnosed as having monoclonal gammopathy based on elevated levels of serum immunoglobulin G. Confocal microscopy showed highly reflective (protein) deposits throughout the entire cornea, with the highest density in the epithelium and anterior stromal keratocytes.

Conclusions

Monoclonal gammopathy, a potential sign of a life-threatening disease, can lead to dense, bilateral corneal deposits. As such changes can occur long before ocular or systemic discomforts appear, an early diagnosis is crucial. Ophthalmologists should be aware of corneal deposits as potential warning signs of monoclonal gammopathy.