Comparing SPEED and OSDI Questionnaires in a Non-Clinical Sample

Purpose

To compare the performance of OSDI and SPEED questionnaires in a non-clinical sample in Pakistan.

Methods

SPEED and OSDI questionnaires were simultaneously administered to a sample of 600 participants in Pakistan with an average age of 31.0 ± 10.1 years.

Results

Mean SPEED scores were calculated according to the OSDI categories and were found to be 3.33 ± 3.44, 5.45 ± 3.77, 7.86 ± 4.33, and 9.39 ± 4.56 for the normal, mild, moderate, and severe groups, respectively. Using Cronbach’s alpha, the total OSDI and SPEED scores were calculated to be 0.924 and 0.879, respectively. A receiver operating curve was plotted, and the area under the curve (AUC) was estimated to be 0.791. Using this curve, the cutoff score for the SPEED questionnaire was found to be 4.00 (P < 0.001).

Conclusion

The SPEED questionnaire can be used as an effective alternative to the OSDI.

Understanding Ocular Visual Function Beyond the Sphere and Cylinder Using Multimodal Imaging

We have presented two interesting cases that demonstrate the use of multimodal imaging in refractive surgery cases. The first case demonstrates a simple capsular contraction causing immense problems of light spread in an otherwise normal trifocal implanted patient. The second is a case of a hidden and problematic refractive surgery that again complicated a trifocal lens surgery. We have made many advancements in understanding the eyes optical elements and must use this to our advantage to help our patients.

The Influence of Tomographic Corneal Characteristics on Epithelial Thickness Profile

Purpose

To understand the influence of tomographic corneal characteristics on the epithelium of normal eyes.

Methods

We scanned a total of 98 eyes of 98 individuals using anterior segment tomography and a spectral-domain optical coherence tomography (OCT) epithelial mapping tool. Only eyes with no previous pathology were included, with a refractive range of +5 diopters (D) to -6 D, intraocular pressure of < 22 mmHg, and no evidence of dry eye (Schirmer’s test 2 value > 5 mm). Corneal curvature metrics were statistically correlated with regional epithelial thickness parameters.

Results

The anterior and posterior corneal surface flat and steep axis, the maximum and minimum curvature, corneal topographic astigmatism, astigmatism polar values, and corneal volume had no statistically significant correlation (p>0.05) with the epithelial thickness. Similarly, anterior corneal surface asphericity had no significant correlation. Posterior surface asphericity had a statistically significant moderate correlation with the epithelium in all areas. Similar results were seen in the multivariate analysis.

Conclusions

None of the front or back surface parameters had any influence on the corneal epithelium except for the posterior surface asphericity. This statistically significant yet clinically insignificant correlation may be enhanced in diseased populations like keratoconus and could indicate epithelial remodeling with early posterior corneal changes.

Distribution and Correlation of Ocular Surface Disease Index Scores in a Non-Clinical Population: The Karachi Ocular Surface Disease Study

Introduction There is increasing recognition of dry eye disease (DED) as a significant factor influencing quality of life in seemingly normal individuals. Our goal was to determine the distribution of Ocular Surface Disease Index (OSDI) scores in non-clinical individuals in Karachi, Pakistan. Methods We distributed OSDI questionnaires to subjects aged > 18 years with no active ocular complaint. Examiners were selected from various areas of the city to administer questionnaires to students and the general population. The OSDI score was grouped as per the following: normal (0-12 points), mild (13-22 points), moderate (23-32 points), and severe (33-100 points). Results We surveyed 2433 individuals with a mean age of 30.7±15.6 years. Additionally, the mean OSDI score was 22.4±18.7. To estimate prevalence, we used two OSDI score cutoffs: >13 (64.4%) and >22 points (43.6%). Statistical significance was found using multivariate regression in the following variables: age (p<0.001), contact lens wear (p<0.001), ocular allergies (p<0.001), hypertension (p<0.001), diabetes (p=0.003), and smoking (p=0.047). When graphing mean age against OSDI score, there was a large jump between the third and fourth decades; thereafter, there was a steady increase. Similarly, when plotting smoking, the score was steady until five years and then there was a sharp incline. Conclusion There was a high prevalence of DED in the studied population. Additionally, many systemic and ocular factors were associated with this disease.

Wide Stromal Mapping Using an Anterior Segment Optical Coherence Tomography

Purpose

To quantify and assess the reproducibility of the corneal stromal thickness profiles captured by the SD-OCT. Secondly, we correlated the zonal thicknesses to the age, gender and axial length.

Methods

We included 227 normal eyes of 227 patients with a maximum hypermetropia of +5 and myopia of –6 diopters (D). Subjects with an intraocular pressure exceeding 22 mm Hg, evidence of cataract formation, history of ophthalmic surgery or disease were excluded. Lastly, reproducibility was evaluated in a subset of 50 participants by means of an identical scan protocol repeated by 2 different OCT operators.

Results

Stromal values were consistently thicker in the peripheral cornea (p<0.001). Age was negatively correlated with approximately every sector of the stroma with notable exceptions of the center (r=0.117, p=0.088) and the superior inner (r=0.057, 0.409), middle (r=0.086, p=0.209) and outer locations (r=0.120, p=0.079). There was no statistical significance in most sectors when looking at the axial length, gender and K1/K2. This method was highly reproducible in terms of both the ICC and COV.

Conclusion

Corneal stromal mapping is highly reproducible and shows a negative correlation to age. Additionally, the periphery of the stroma is consistently thicker to the center. Other variables like gender and axial length show no relationship to the corneal stroma.

Effect of Demographic Variables on the Regional Corneal Pachymetry

PURPOSE

The measurement of corneal thickness by corneal pachymetry provides valuable information in the setting of corneal disease; however, spectral-domain optical coherence tomography (SD-OCT)-based assessment of different corneal sectors has been scarce in Pakistan.

DESIGN

We aimed to obtain a whole-corneal thickness map using SD-OCT and to evaluate its correlation with age, sex, and axial length.

METHODS

Our study included 214 subjects with healthy corneas; each eye was scanned with an SD-OCT covering a 9-mm diameter, and reproducibility was evaluated in a subset of 50 participants by means of an identical scan protocol repeated by 2 different OCT operators.

RESULTS

Our analysis revealed corneal thickness to be thinnest inferotemporally whereas thickest in the superior and superonasal quadrants. No statistically significant differences could be detected between male and female participants with respect to corneal thickness, age, intraocular pressure, axial length, and refractive errors. However, we identified a significant negative correlation between age and corneal thickness in all corneal sections, excluding the inner and middle superior, inner superonasal, and inner and middle superotemporal quadrants. Conversely, the correlation between axial length and corneal thickness was found to be positive in the central region (P = 0.03, R = 0.149), the outer inferotemporal quadrant (P = 0.012, R = 0.171), throughout the temporal quadrant (P = 0.024, R = 0.154 for inner; P = 0.025, R = 0.153 for middle; P = 0.006, R = 0.186 for outer), and in the inner superotemporal quadrant (P = 0.018, R = 0.162).

CONCLUSIONS

Different corneal sectors may interact heterogeneously with patient-related characteristics. This may provide incentive to evaluate whole-corneal thickness as a distinct parameter for clinical identification of disease processes.

Macular vascular density at the superficial capillary plexus using the optical coherence tomography angiography

Purpose

The aim of this study was to assess the effects of age, gender, axial length and retinal thickness on the vascular density in a normal population using the Optovue optical coherence tomography angiography (OCT-A).

Methods

A total of 209 eyes of 209 healthy subjects were scanned using the OCT-A on an outpatient basis. Patients were 20–75 years of age. The built-in software covered a 3×3 mm circle centered at the macula. The circle was divided into five sectors: a 1 mm central foveal circle and an upper, lower, nasal and temporal sector each spanning 1–3 mm away from the central circle. The vascular density (VD) at the superficial capillary plexus was measured, which spanned from the inner limiting membrane to the inner plexiform layer.

Results

The fovea was the least dense area (32.5%±5.9%), and the temporal area was the densest (52.4%± 4.4%). Similarly, the fovea was the thinnest part of the retina (237.8±20.7 µm); however, the nasal sector was the thickest (308.5±15.1 µm). We found a correlation of the retinal thickness (r=0.541, P<0.001) with VD only at the fovea. Similarly, males had a greater density at the fovea (P=0.002). All regions significantly and negatively correlated with age even after adjusting for axial length. The age sees a decline in the density after the fifth decade where the variability also seems to increase.

Conclusion

This study provides normative data for the Pakistani population. Additionally, it demonstrates that VD is affected by the retinal thickness at the fovea and the density begins to decline after the fifth decade.

Wide Corneal Epithelial Mapping Using an Optical Coherence Tomography

Purpose

To map the corneal epithelium using a map measuring 9 mm in diameter and view the effects of age, sex, and axial length. Additionally, we wanted to demonstrate the reproducibility of this technique.

Methods

We calculated the epithelial thickness in 220 individuals using an SD-OCT machine with the newly released commercially available algorithm. We included normal eyes with refractive errors between +5 and -6 diopters (D). We excluded patients with an intraocular pressure of >22 mm Hg, history of cataract, previous ocular surgery, or disease and those with corneal pathology. Additionally, we excluded patients with evidence of systemic disease or pregnancy. Lastly, reproducibility was measured in 50 individuals.

Results

We found the center of the corneal epithelium to be thicker than the peripheral in all zones except the nasal (P = 0.124). The superior quadrant was found to be the thinnest while the inferior was the thickest. Males had a thicker epithelium in all locations except the superior outer section (P = 0.123). Three zones had a weak correlation with age: outer superior (P = 0.039, R = -0.152); outer temporal (P = 0.042, R = -0.150); and outer superior temporal (P = 0.011, R = -0.187). There was no significant relationship with the axial length. We found good to excellent reproducibility when using this technique in the central as well as the peripheral cornea.

Conclusions

We provide a comprehensive study in healthy, normal eyes using a novel algorithm to map the corneal epithelium with a wide diameter. This study can be used as a reference for future research.

Assessing reproducibility and the effects of demographic variables on the normal macular layers using the Spectralis SD-OCT

Purpose

To quantify and view the possible influence of demographic variables on normal macular layers. Additionally, we wanted to assess the reproducibility using the Spectralis SD-OCT.

Methods

A Spectralis SD-OCT machine using a commercially available algorithm was used to scan 242 healthy subjects in an outpatient setting. We examined retinal thicknesses in seven layers: retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL) and retinal pigment epithelium (RPE). Combined retinal thicknesses were expressed as inner retinal layer (IRL), photoreceptor layer (PL) and total retinal thickness (TRT). Measurements were taken from each of the nine sectors defined by the Early Treatment Diabetic Retinopathy Study; the center was the fovea, the inner circle (IC) was 1–3 mm away, and the outer circle (OC) was 3–6 mm away.

Results

The TRT was thickest inferiorly in the IC, and superiorly in the OC. The RNFL (P=0.030), GCL (P=0.006), IPL (P=0.006), IRL (P=0.030), PL (P<0.001) and TRT (P=0.001) were found to be thicker in males. The GCL (r=0.078, P=0.001), IPL (r=0.079, P=0.001), IRL (r=0.072, P=0.002), PL (r=0.076, P=0.001) and TRT (r=0.090, P<0.001) were found to decrease with age. The INL (r=0.060, P=0.010), ONL (r=0.078, P=0.001), and RPE (r=0.066, P=0.004) were inversely related to axial length. Excellent reproducibility was observed in all layers.

Conclusion

Our study shows differences in various retinal layers according to age, gender, and axial length. Additionally, we demonstrate excellent reproducibility of this algorithm using the Spectralis SD-OCT.

Visual and Refractive Outcomes of Topography-guided Laser-assisted In Situ Keratomileusis in Virgin Eyes

Introduction

We wanted to assess the efficacy, predictability, and stability of topography-guided, laser-assisted in situ keratomileusis (TGL) on normal untreated eyes with a preoperative best corrected visual acuity (BCVA) of 20/20.

Methods

This was a retrospective, non-randomized, and single arm study evaluating the outcomes of TGL in eyes with a preoperative BCVA of 20/20. We included 50 eyes of 50 patients who presented to the Hashmanis Hospital, Pakistan and were followed for six months postoperatively. All eyes underwent treatment using the Alcon Wavelight Allegro Topolyzer (Alcon Laboratories, Inc., TX, USA).

Results

The mean preoperative sphere, cylinder, and spherical equivalent (SE) values were -4.3 ± 1.6 dioptres (D), -1.0 ± 0.8 D, and -4.8 ± 1.8 D. On day one these values were 0.2 ± 0.8 D, -0.5 ± 0.3, and  0.3 ± 0.8, respectively, and on month six they were -0.1 ± 0.6, -0.5 ± 0.3, and -0.4 ± 0.6 D, respectively. On postoperative day one and month six, 86% and 94% of eyes had a UCVA of 20/20 or better, respectively. Two eyes (4%) had an SE change of greater than 0.5 D from three to six months.

Conclusion

Our study demonstrates good efficacy, predictability, and stability of eyes undergoing TGL with a follow-up of six months.

Three-dimensional mapping of peripapillary retinal layers using a spectral domain optical coherence tomography

Purpose

To map and view the effects of age, gender, and axial length on seven individual retinal layers around the optic nerve head (ONH).

Methods

We scanned 242 healthy patients using the Spectralis spectral domain optical coherence tomography in an outpatient setting. The layers were observed on the Early Treatment Diabetic Retinopathy Study sectors using the standard Spectralis Family Acquisition Module 6.0.11.0. The center was the ONH, the inner circle (IC) was 1-3 mm away, and the outer circle (OC) was 3-6 mm away. The seven layers were retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), and retinal pigment epithelium (RPE). Additionally, we calculated the mean thickness of two combined layers: inner retinal layer (IRL) and photoreceptor layer (PL). Finally, we measured the mean of the total retinal thickness (TRT).

Results

The TRT was highest at the inferior end in the IC and at the nasal end in the OC. The RPE (p<0.001) and PL (p<0.001) were thicker in males; however, the IRL (p=0.015) was thicker in females. We found that the RNFL (p<0.001, r=0.139), GCL (p<0.001, r=0.116), IPL (p=0.016, r=0.059), INL (p<0.001, r=0.104), OPL (p=0.009, r=0.064), ONL (p<0.001, r=0.157), RPE (p=0.001, r=0.079), IRL (p<0.001, r=0.190), PL (p=0.030, r=0.053), and TRT (p<0.001, r=0.191) correlated negatively with age. The axial length significantly and negatively correlated at the GCL (p=0.003, r=0.093), IPL (p=0.020, r=0.072), INL (p=0.018, r=0.073), ONL (p<0.001, r=0.110), IRL (p=0.003, r=0.092), and TRT (p=0.003, r=0.094). We found poor reproducibility in the IC; however, this was excellent in the OC.

Conclusion

We found significant differences in layers according to age, gender, and axial length. Additionally, reproducibility can be improved by altering the algorithm to account for the ONH parameters.

Corneal Collagen Cross-Linking Combined with an Artiflex Iris-Fixated Anterior Chamber Phakic Intraocular Lens Implantation in a Patient with Progressive Keratoconus

We present here the case of a 24-year-old male who experienced progressive keratoconus and vision loss which adversely affected his ability to carry out everyday tasks. This landed him in the Hashmanis Hospital for consultation. He had a preoperative best corrected visual acuity of 6/12. He underwent multiple Oculus Pentacam examinations, which showed progressive keratoconus. Corneal collagen cross-linking (CXL) was performed to stabilize his cornea and, subsequently, an Artiflex anterior chamber iris-fixated phakic intraocular lens (ACIF-PIOL) was implanted to alleviate his refractive errors. The patient achieved a postoperative uncorrected visual acuity of 6/12. This report shows that CXL combined with ACIF-PIOL can be safe and effective in those with progressive keratoconus.

A Comparison of Visual Outcomes and Patient Satisfaction Between Photorefractive Keratectomy and Femtosecond Laser-Assisted In Situ Keratomileusis

Purpose

To compare visual outcomes and satisfaction among patients of photorefractive keratectomy (PRK; Wavelight EX 500, Alcon, Ft Worth, TX, USA) and femtosecond laser-assisted in situ keratomileusis (FAL; Wavelight FS 200 laser and Wavelight EX 500, Alcon, Ft Worth, TX, USA).

Methods

We performed a retrospective study of 409 eyes in 207 patients that underwent either PRK (n=90) or FAL (n=117) at the two centers of Hashmanis Hospital, Karachi, Pakistan. The included refractive outcomes were sphere diopters (D), cylinder D, and spherical equivalent D. Additionally, visual acuities were included. All of these were assessed preoperatively and at the one-month postoperative check-up. Patient satisfaction was gauged at the time of chart review by contacting the patient.

Results

When looking at the postoperative outcomes, we found all values to be statistically significant (p<0.001) with superior outcomes in the FAL cohort. Additionally, 90% and 15% of eyes achieved a postoperative uncorrected visual acuity (UCVA) of 20/20 in FAL and PRK, respectively. Furthermore, the efficacy indexes of the FAL and PRK arms were 1.00 and 0.82, respectively. The predictability of the procedures were 92.1% and 64.9%, respectively. Lastly, 93.3% of patients were satisfied with FAL and 95.7% with PRK.

Conclusion

Our study shows superior visual outcomes in patients undergoing FAL. However, we found a higher satisfaction rate in those that underwent PRK, perhaps due to the higher cost of FAL.

Traumatic dislocation of phakic anterior chamber iris-claw intraocular lens: A case report

We are presenting a traumatic dislocation of a Phakic intraocular lens (PIOL) secondary to a blunt trauma to the right eye. The patient presented with a sudden blurring of vision with no other associated injury. His slit lamp examination showed disenclavation of the temporal clip and pre-operatively his best spectacle-corrected visual acuity (BSCVA) was 6/36. The patient was brought to the operating room where his lens was repositioned and re-enclaved. He had a complete restoration of vision with a BSCVA of 6/9 and an endothelial cell count of 2786/mm2. We conclude that a traumatic dislocation of an iris-claw PIOL can be successfully corrected without immediate postoperative complications and endothelial cell count loss.

Effect of age, sex, and refractive errors on central corneal thickness measured by Oculus Pentacam®

BACKGROUND

Central corneal thickness (CCT) can be used to assess the corneal physiological condition as well as the pathological changes associated with ocular diseases. It has an influence on the measurement of intraocular pressure and is being used as a screening tool for refractive surgery candidates. The aim of this study was to determine the median CCT among normal Pakistani population and to correlate CCT with age, sex, and refractive errors.

METHODS

We conducted a retrospective analysis of 5,171 healthy eyes in 2,598 patients who came to Hashmanis Hospital, Karachi, Pakistan. The age of the patients ranged from 6 to 70 years. The refractive error was gauged by an auto-refractometer, and CCT was measured using Oculus Pentacam^®.

RESULTS

The median CCT of our study was 541.0 μm with an interquartile range (IQR) of 44.0 μm. The median age was 26.0 years (IQR: 8.0). Median spherical equivalent (SE) of the patients was -4.3 D (IQR: 3.3) with the median sphere value as -4.0 D (IQR: 3.8). Lastly, the median cylinder was -1.0 D (IQR: 1.3). Age has a weak negative correlation with CCT (r=-0.058) and shows statistical significance (P<0.001). Additionally, males had thinner CCT readings than females (P=0.001). The cylinder values, on the other hand, had a significant (P=0.004) and positive correlation (r=0.154). Three values showed no significant correlation: sphere (P=0.100), SE (P=0.782), and the left or right eye (P=0.151).

CONCLUSION

Among the Pakistani population, CCT was significantly affected by three variables: sex, age, and cylinder. No relationship of CCT was observed with the left or right eye, sphere, and SE.

Reasons for Refusing Laser-Assisted in Situ Keratomileusis in a Pakistani Population

Purpose

To study and analyze the reasons for not performing laser-assisted in-situ keratomileusis (LASIK) surgery in Pakistan.

Methods

This is a retrospective observational review of the patients who presented for LASIK surgery during January 2014 to September 2016 at the Hashmanis Hospital refractive surgery facility in Karachi, Pakistan.

Results

A total of 6005 eyes in 3512 patients presented for LASIK surgery. Out of these, a total of 1795 eyes (29.9%) of 899 patients (25.6%) were rejected. The most common cause for not performing LASIK surgery was found to be increased risk of postoperative ectasia seen in 534 (29.75%) eyes. In 275 (15.32%) eyes, the surgery could not be performed because of affordability of procedure or unscientific apprehensions of the patient. Keratoconus was seen in 268 (14.93%) eyes.

Conclusion

The patients presenting for LASIK surgery need extensive screening as the large proportion of patients may have corneal structural for not performing this procedure. The cost of the procedure plays its role as does the unscientific beliefs amongst the patients.

Comparison of visual acuity, refractive outcomes, and satisfaction between LASIK performed with a microkeratome and a femto laser

Purpose

To compare refractive outcomes, visual acuities, and satisfaction of patients between those treated with laser-assisted in situ keratomileusis (LASIK) using a Hansatome microkeratome (HM) and femto-assisted laser (FAL).

Methods

This was a retrospective analysis of 1,366 eyes in 687 patients who underwent LASIK with an HM (n=1,137) and an FAL (n=229) at the two centers of Hashmanis Hospital, Karachi, Pakistan. Refractive outcomes, including sphere, cylinder, and spherical equivalent in diopters (D), and visual acuities were assessed both preoperatively and at 1 month follow-up. Patient satisfaction was gauged by contacting the patient at the time of chart review.

Results

The postoperative median sphere, cylinder, and spherical equivalent values for those treated with FAL were 0.3±0.7 (−5.5–1.8), −0.5±0.6 (−5.0–1.0), and 0.0±0.7 (−6.0–1.6), respectively. For the HM arm, they were 0.0±1.28 (−10.8–6.8), −0.5±0.5 (−4.5–1.5), and −0.3±1.3 (−11.6–6.8), respectively. All preoperative values were statistically insignificant between the groups, while postoperative values were significant with P-values <0.001. Predictability and efficacy index was higher for the FAL (92.1%, 1.00) than the HM group (82.2%, 0.84). Similarly, patient satisfaction was slightly higher for those treated with FAL (93.3%) than HM (91.4%).

Conclusion

Our large retrospective analysis of eyes that have undergone LASIK using HM and FAL shows superior refractive outcomes in the latter, with special regard to procedural efficacy and predictability.