Clinical Profile on Keratoconus Presenting at A Tertiary Eye Care Centre- Tilganga Institute of Ophthalmology

Introduction: Keratoconus (KC), is a bilateral, noninflammatory degenerative disease of the cornea which is characterized by progressive corneal ectasia and loss of visual function. The onset of KC is commonly seen at puberty and affects approximately 1 in 2000 in the general population. Objective: The aim of this study was to assess the clinical profile of keratoconus in the tertiary eye centre in Nepal. Material and methods: It is a retrospective, hospital based, consecutive study from June 2017 to May 2018. A total of 66 patients (114 eyes) were diagnosed cases of Keratoconus presented in Cornea clinic of Tilganga institute of Ophthalmology. Parameters investigated included patients’ demography, keratometric readings, visualacuity and manifest refraction. Classification of keratoconus was based on Amslern-Krumeich grading system (modified). Results: The mean age of subjects was 18.73 (range: 10-65). Male/female distribution was 48 (72.7%) and 18 (27.3%) respectively. 48 (72.7%) had bilateral keratoconus and 18 (27.3%) were unilateral. Mean Uncorrected visual acuity (UCVA) was 0.80 (range: 0.01-1.00), mean visual acuity ( VA) with spectacle correction was 0.47 (range: 0.01-1.00). Mean spherical amount of refractive was –2.17 (range: −0.50 to −17.00D) and mean cylindrical amount of refraction was -2.85 (range: 0.00 to −6.00). Mean spherical equivalent (SE) of refraction was −4.26 (range: −0.50 to −22.50D). Mean flattest keratometric reading (K1) was 49.63 (range: 40.63-76.70D) and mean steepest keratometric reading (K2) was 53.14 (range: 41.63-73.21D). Mean average keratometric reading was 51.43 (range: 41.63-72.10D). Regarding disease severity, 35.68% of subjects were classified as mild keratoconus, 29.73% as moderate keratoconus, 9.73% as advance keratoconus, while 24.86% were found with the severestage of keratoconus. 78.9% of total eyes presented with minimum pachymetry of 401 to 500 mm. Conclusion: Clinical profile of Nepalese keratoconus patients looks similar to that reported earlier worldwide. The condition was found to manifest at a younger age and was more common in males.

Download Full-text

Topographically Guided Two-Step LASIK and Standard LASIK in the Correction of Refractive Errors after Penetrating Keratoplasty

European Journal of Ophthalmology ◽

10.1177/112067210901900404 ◽

2009 ◽

Vol 19 (4) ◽

pp. 535-543 ◽

Cited By ~ 4

Author(s):

Leopoldo Spadea ◽

Massimo Saviano ◽

Angela Di Gregorio ◽

Domenico Di Lodovico ◽

Fabio De Sanctis

Keyword(s):

Visual Acuity ◽

Penetrating Keratoplasty ◽

Laser In Situ Keratomileusis ◽

Refractive Errors ◽

Manifest Refraction ◽

Uncorrected Visual Acuity ◽

The Mean ◽

Group 2 ◽

Group 1

Purpose To evaluate in a long-term period the effectiveness and safety of topographically guided two-step laser in situ keratomileusis (LASIK) and standard LASIK technique in the correction of refractive errors after successful penetrating keratoplasty (PKP) for keratoconus. Methods At least 2 years after PKP and 6 months after removal of all sutures, 15 eyes of 15 patients (Group 1; mean manifest refraction spherical equivalent (MRSE) −7.23 D ± 3.42 SD) were submitted to standard LASIK and 15 eyes of 15 patients (Group 2; mean MRSE −4.37 D ± 1.97 SD) to a topographically guided two-step LASIK procedure (first the flap and at least 2 weeks later the laser ablation). In all cases, a superior hinged corneal flap (160 μm/9.5 mm) was created. Results After a follow-up of 36 months, in Group 1 the mean uncorrected visual acuity (UCVA) was 0.51 logarithm of the minimum angle of resolution (logMAR) ± 0.41 SD and the mean best-corrected visual acuity (BCVA) was 0.03 logMAR ± 0.05 SD, with a mean MRSE of −1.57 D ± 2.65 SD. In Group 2, the mean UCVA was 0.28 logMAR ± 0.24 SD and the mean BCVA was 0.01 logMAR ± 0.03 SD, with a mean MRSE of −0.07 D ± 1.00 SD. In both groups, no complications were observed. Conclusions After a long follow-up period, both topographically guided two-step LASIK and standard LASIK could be considered effective and safe tools in the correction of refractive errors after successful PKP for keratoconus.

Download Full-text

Clinical Effect and Rotational Stability of TICL in the Treatment of Myopic Astigmatism

Journal of Ophthalmology ◽

10.1155/2020/3095302 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7

Author(s):

Manhui Zhu ◽

Linling Zhu ◽

Qiujian Zhu ◽

Cailian Xu ◽

Peng Yu ◽

...

Keyword(s):

Risk Factors ◽

Visual Acuity ◽

Rotational Stability ◽

Spherical Equivalent ◽

Implantable Collamer Lens ◽

Manifest Refraction ◽

Efficacy Index ◽

The Mean ◽

Myopic Astigmatism ◽

High Myopic Astigmatism

Purpose. To investigate the clinical outcomes and possible risk factors associated with rotational stability after the implantation of a V4c toric implantable Collamer lens (TICL) for the correction of moderate to high myopic astigmatism. Methods. A total of 112 eyes of 66 patients with moderate to high myopic astigmatism underwent TICL implantation. All patients were followed up for more than 1 year. The uncorrected and best-corrected visual acuity (UCVA and BCVA), astigmatism and spherical equivalent, intraocular pressure, vault, endothelial cell morphometry, and rotation of the TICL axis were assessed at l day, 1 week, 1 month, 3 months, 6 months, and 12 months postoperatively. Postoperative rotation was defined as the angle between the intended axis and the achieved axis. Regression analysis was used to investigate the possible risk factors for TICL rotation postoperatively. Results. The mean efficacy index and safety index 12 months postoperatively were 1.03 ± 0.09 and 1.05 ± 0.10, respectively. All patients had the same or better visual acuity than preoperatively. The mean astigmatism value decreased from −1.86 ± 0.79 D preoperatively to −0.37 ± 0.35 D. The mean absolute axis deviation of the TICL at the last follow-up was 2.75 ± 2.04° (range, 0°∼11°). The mean manifest refraction spherical equivalent (MRSE) changed from -9.04 ± 2.67 D preoperatively to −0.67 ± 0.51 D postoperatively. The logistic regression demonstrated that the absolute degree of TICL rotation had a significant association with the fixation angle of the TICL and the size of the lens ( P = 0.003 , P = 0.026 , resp.). Conclusion. The results of our study support that TICL implantation is safe, effective, and predictable in the treatment of moderate to high myopic astigmatism, with relatively good postoperative rotational stability.

Download Full-text

Use of new-generation hybrid contact lenses for managing challenging corneas

European Journal of Ophthalmology ◽

10.1177/1120672120942757 ◽

2020 ◽

pp. 112067212094275

Author(s):

Ibrahim Inan Harbiyeli ◽

Elif Erdem ◽

Puren Isik ◽

Meltem Yagmur ◽

Reha Ersoz

Keyword(s):

Visual Acuity ◽

Medical Records ◽

Contact Lenses ◽

Corrected Visual Acuity ◽

Manifest Refraction ◽

Uncorrected Visual Acuity ◽

The Mean ◽

New Generation ◽

Generation Hybrid ◽

Irregular Astigmatism

Introduction: To evaluate the safety and efficacy of new-generation hybrid contact lenses (HCL) among patients with irregular astigmatism. Methods: Medical records of 25 patients fit with new-generation HCL (Eyebrid® and AirFlex®) were retrospectively reviewed. The data collected included etiology of irregular astigmatism, uncorrected visual acuity, manifest refraction, spectacle-corrected visual acuity (S-CDVA), steep / flat keratometric values, corneal astigmatism, records of rigid / soft CL fitted before HCL, all parameters of the trial lenses, and the final prescribed HCL parameters and HCL-CDVA. Results: The study included 34 eyes from 25 patients (nine females and 16 males) with an average age of 29 ± 13 (ranging from 8–56) years. In total, 25 eyes with keratoconus, four with post - keratoplasty astigmatism, three with irregular astigmatism due to corneal trauma and two with residual astigmatism after radial keratotomy were fit with HCL. The mean S-CDVA (logMAR) improved significantly from 0.76 ± 0.41 to 0.14 ± 0.15 with HCL ( p < 0.01). The most common indication for HCL was inability to fit with rigid gas permeable (RGP) lenses (22 eyes). The average number of lenses to successful fit was 1.4 (mode, 1; median, 1) and ideal fit was achieved with the first trial lens in 25 eyes (73%). Seven patients (nine eyes, 36%) discontinued lens use within the first 6 months because of discomfort (six eyes, 24%), ocular allergy (two eyes, 8%) and tearing of contact lens (one eye, 4%). Discussion: New-generation HCL may be a suitable option for fitting challenging corneas with irregular astigmatism that cannot be rehabilitated efficiently with rigid lenses.

Download Full-text

The evaluation of a web-based tool for measuring the uncorrected visual acuity and refractive error in keratoconus eyes: A method comparison study

PLoS ONE ◽

10.1371/journal.pone.0256087 ◽

2021 ◽

Vol 16 (8) ◽

pp. e0256087

Author(s):

Marc B. Muijzer ◽

Janneau L. J. Claessens ◽

Francesco Cassano ◽

Daniel A. Godefrooij ◽

Yves F. D. M. Prevoo ◽

...

Keyword(s):

Visual Acuity ◽

Refractive Error ◽

Mean Difference ◽

Index Test ◽

Spherical Equivalent ◽

Reference Test ◽

Web Based ◽

Manifest Refraction ◽

Uncorrected Visual Acuity ◽

The Web

Purpose To evaluate the outcome of a web-based digital assessment of visual acuity and refractive error, compared to a conventional supervised assessment, in keratoconus patients with complex refractive errors. Material and methods Keratoconus patients, aged 18 to 40, with a refractive error between -6 and +4 diopters were considered eligible. An uncorrected visual acuity and an assessment of refractive error was taken web-based (index test) and by manifest refraction (reference test) by an optometrist. Corrected visual acuity was assessed with the prescription derived from both the web-based tool and the manifest refraction. Non-inferiority was defined as the 95% limits-of-agreement (95%LoA) of the differences in spherical equivalent between the index and reference test not exceeding +/- 0.5 diopters. Agreement was assessed by a Bland-Altman analyses. Results A total of 100 eyes of 50 patients were examined. The overall mean difference of the uncorrected visual acuity measured -0.01 LogMAR (95%LoA:-0.63–0.60). The variability of the differences decreased in the better uncorrected visual acuity subgroup (95%LoA:-0.25–0.55). The overall mean difference in spherical equivalent between the index and reference test exceeded the non-inferiority margin: -0.58D (95%LoA:-4.49–3.33, P = 0.008). The mean differences for myopic and hyperopic subjects were 0.09 diopters (P = 0.675) and -2.06 diopters (P<0.001), respectively. The corrected visual acuities attained with the web-based derived prescription underachieved significantly (0.22±0.32 logMAR vs. -0.01±0.13 LogMAR, P <0.001). Conclusions Regarding visual acuity, the web-based tool shows promising results for remotely assessing visual acuity in keratoconus patients, particularly for subjects within a better visual acuity range. This could provide physicians with a quantifiable outcome to enhance teleconsultations, especially relevant when access to health care is limited. Regarding the assessment of the refractive error, the web-based tool was found to be inferior to the manifest refraction in keratoconus patients. This study underlines the importance of validating digital tools and could serve to increase overall safety of the web-based assessments by better identification of outlier cases.

Download Full-text

Three-year Clinical Outcomes of Aspheric Micro-monovision LASIK for Correction of Presbyopia and Myopic Astigmatism

10.21203/rs.2.15661/v2 ◽

2020 ◽

Author(s):

Fang Liu ◽

Ting Zhang ◽

Quan Liu

Keyword(s):

Visual Acuity ◽

Spherical Equivalent ◽

Distance Visual Acuity ◽

Uncorrected Distance Visual Acuity ◽

High Satisfaction ◽

Manifest Refraction ◽

Corrected Distance Visual Acuity ◽

Uncorrected Visual Acuity ◽

Registration Number ◽

Myopic Astigmatism

Abstract Background: To investigate the long-term safety and efficacy of aspheric micro-monovision LASIK for the correction of presbyopia and myopic astigmatism. Methods: In total, 114 eyes of 57 patients with a mean age of 48 ± 4.05 years (range: 43 to 62 years) who were undergoing aspheric micro-monovision LASIK treatment were enrolled. Visual acuity, manifest refraction, amplitude of accommodation, contrast sensitivity, entire eye aberrations and patients’ subjective ratings were evaluated from 1 day to 3 years postoperatively. Results: None of the eyes showed a spherical equivalent change of over 0.75 D between 3 months and 3 years, while 95% of the eyes were within ±0.50 D of the target correction of the spherical equivalent. The percentage of patients showing monocular uncorrected distance visual acuity ≥20/20 was 95%, and all eyes achieved a visual acuity of 20/25 or better. The percentage of patients showing binocular uncorrected near visual acuity ≥J2 was 93%, and all patients achieved a visual acuity of J4 or better. Ninety-one percent of the patients had an uncorrected visual acuity of 20/20 in both eyes and J2 or better binocular visual acuity. Six of 108 eyes (6%) lost 1 line, and no eyes lost 2 lines of corrected distance visual acuity. The overall satisfaction score for surgery was 93 ± 6. Conclusions: Aspheric micro-monovision LASIK using the Carl Zeiss Meditec MEL 80 Platform was an efficacious option for older myopic patients with presbyopia. Three-year postoperative outcomes in the Chinese population indicated improvements in uncorrected binocular vision at far and near distances with high satisfaction. Trial registration: The registration number is ChiCTR-IPC-15005842, and the date of registration is January 16, 2015.

Download Full-text

The evaluation of a web‐based tool for measuring the uncorrected visual acuity and refractive error in keratoconus eyes: a prospective open‐label method comparison study

10.1101/2021.03.01.21252664 ◽

2021 ◽

Cited By ~ 1

Author(s):

Marc B Muijzer ◽

Janneau L J Claessens ◽

Francesco Cassano ◽

Daniel A Godefrooij ◽

Yves F D M Prevoo ◽

...

Keyword(s):

Visual Acuity ◽

Refractive Error ◽

Intraclass Correlation ◽

Mean Difference ◽

Spherical Equivalent ◽

Reference Test ◽

Web Based ◽

Manifest Refraction ◽

Uncorrected Visual Acuity ◽

The Web

AbstractPurposeTo evaluate the outcome of a web‐based digital assessment of visual acuity and refractive error, compared to a manifest refraction assessment, in keratoconus patients with complex refractive errors.Material and methodsKeratoconus patients, aged 18 to 40, with a refractive error between ‐6 and +4 diopters were eligible. Each participant subsequently underwent an uncorrected visual acuity and a refractive assessment. Refractive error was assessed with the web‐based tool (index test), an autorefractor, and a manifest refraction (reference test) by an optometrist. Corrected visual acuity was assessed with the web‐based and manifest refractive prescription. Non‐inferiority was defined as the 95% limits‐of‐agreement (95%LoA) of the differences in spherical equivalent between the index and reference test not exceeding +/‐ 0.5 diopters. Agreement was assessed by an intraclass correlation coefficient and Bland‐Altman analyses.ResultsA total of 100 eyes of 50 patients were examined. The overall mean difference of the uncorrected visual acuity measured ‐0.01 LogMAR (95%LoA:‐0.63–0.60). The variability decreased in the high uncorrected visual acuity subgroup (mean difference: 0.15 LogMAR, 95%LoA:‐0.25–0.55). The intraclass correlation coefficient of the three refractive assessments was 0.32. The overall mean difference in spherical equivalent between the index and reference test measured ‐0.58 diopters (95%LoA:‐4.49 – 3.33, P=0.008). The mean differences for myopic and hyperopic subjects were 0.09 diopters (P=0.675) and ‐2.06 diopters (P<0.001), respectively.ConclusionsOur results show promising results in the ability of the web‐based tool to remotely assess visual acuity in keratoconus patients. The agreement is better in higher visual acuity ranges and could provide physicians with an objective measurement to enhance teleconsultations, especially relevant when access to health care is limited. The assessment of the refractive error using the web‐based tool was found to be inferior to the manifest refraction and deserves further training of the tools algorithm.

Download Full-text

Visual Performance after a Unilateral or Bilateral Implantation of Enlarged Depth-of-Focus Intraocular Lens in Patients with Cataract: A Prospective Clinical Trial

Journal of Ophthalmology ◽

10.1155/2019/2163809 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8

Author(s):

Se Hyun Choi ◽

Hyo kyung Lee ◽

Chang Ho Yoon ◽

Mee Kum Kim

Keyword(s):

Visual Acuity ◽

Intraocular Lens ◽

Mean Absolute Error ◽

Absolute Error ◽

Numerical Error ◽

Spherical Equivalent ◽

Depth Of Focus ◽

Manifest Refraction ◽

The Mean ◽

Best Fit

Purpose. To investigate visual performances after a unilateral or bilateral implantation of enlarged depth-of-focus intraocular lens in patients with cataract. Methods. In this prospective study, uneventful phacoemulsification and TECNIS® Symfony intraocular lens implantation were performed in 20 eyes of 17 patients. At postoperative 1, 4, and 12 weeks, the logarithm of the minimal angle of resolution visual acuity at far, intermediate, and near distances and the spherical equivalent in manifest refraction and automated refraction were measured. A questionnaire was used to investigate glare, spectacle dependency, and satisfaction at 12 weeks. The mean numerical error and mean absolute error were compared between intraocular lens formulas to assess the best-fit formula. Results. The logarithm of the minimal angle of resolution visual acuity significantly improved to 0.02 at far, 0.02 at intermediate, and 0.27 at near distances at 12 weeks (p<0.05). Spherical equivalent was −0.79 D on automated refraction and was significantly lower than −0.26 D measured on manifest refraction. Patients’ satisfaction score was 9.06, 8.94, and 6.65 for far, intermediate, and near distances, respectively. Near glasses were required in 5 patients and 2 patients complained of photic phenomenon. Visual performances were not significantly different between bilateral and unilateral implanted patients. No patients reported bilateral imbalance due to unilateral surgery. The mean numerical error was closest to 0 D using the Barrett Universal II formula. The mean absolute error was not significantly different between these formulas. Conclusion. Unilateral or bilateral implantation of the enlarged depth-of-focus intraocular lens seems to be equally effective in improving visual performances in patients with cataract.

Download Full-text

Transepithelial photorefractive keratectomy on the same day of the initial consultation for the correction of myopia

European Journal of Ophthalmology ◽

10.1177/11206721211033484 ◽

2021 ◽

pp. 112067212110334

Author(s):

Olga Reitblat ◽

Assaf Gershoni ◽

Michael Mimouni ◽

Eitan Livny ◽

Yoav Nahum ◽

...

Keyword(s):

Visual Acuity ◽

Clinical Outcomes ◽

Photorefractive Keratectomy ◽

Spherical Equivalent ◽

Initial Visit ◽

Safety Outcome ◽

Uncorrected Visual Acuity ◽

Safety Indices

Purpose: To examine the clinical outcomes, efficacy, safety, and predictability of transepithelial photorefractive keratectomy (Trans-PRK) operations performed on the day of the first screening visit in comparison with operations scheduled at a following appointment. Methods: Data of consecutive patients with myopia of various degrees, who underwent Trans-PRK, were retrospectively analyzed. Findings were compared between patients who underwent Trans-PRK on the same day of first consultation to patients that underwent surgery at subsequent visits, following initial consultation on a different day. Results: The study included 599 eyes treated on the initial visit day and 1936 eyes treated on a subsequent visit. Mean final spherical equivalent was close to emmetropia in both groups ( p = 0.183). Efficacy indices were 0.928 ± 0.192 in the initial-visit group and 0.945 ± 0.163 in the second-visit group ( p = 0.152). Safety indices were 0.954 ± 0.156 and 0.955 ± 0.151 ( p = 0.707), respectively. No differences between the groups were seen in uncorrected visual acuity (UDVA) of ⩾20/20, ⩾20/25, and ⩾20/32. Only the sub-analysis of patients reaching UDVA of 20/40 or better was slightly lower in the first-visit (95.5%) compared with the second-visit group (97.9%, p = 0.001). Results of attempted correction within ±0.50 D were: 63.3% and 69.0%, respectively ( p = 0.009). Complications profiles in the two groups were comparable. Conclusions: Trans-PRK completed on the day of the first screening appointment demonstrated a similar safety outcome compared with subsequent-visits procedures, and slightly lower, yet comparable, results regarding efficacy and predictability.

Download Full-text

Corneal densitometry in patients with keratoconus undergoing intrastromal Ferrara ring implantation

European Journal of Ophthalmology ◽

10.1177/11206721211020631 ◽

2021 ◽

pp. 112067212110206

Author(s):

Pablo Felipe Rodrigues ◽

Bernardo Kaplan Moscovici ◽

Guilherme Ferrara ◽

Luciano Lamazales ◽

Marcela Mara Silva Freitas ◽

...

Keyword(s):

Visual Acuity ◽

Medical Records ◽

Spherical Equivalent ◽

Interventional Study ◽

Data Comparison ◽

Corneal Densitometry ◽

Corrected Visual Acuity ◽

Ring Segment ◽

The Mean

Objective: Evaluation of central corneal densitometry changes following Ferrara corneal ring segment implantation in patients with keratoconus, especially the correlation between corneal densitometry and keratometry. Methods: Retrospective, non-comparative, interventional study based on the review of medical records of patients diagnosed with keratoconus who underwent Ferrara corneal ring segment implantation. Pre and post-operative corneal densitometry measurements obtained with Pentacam HR (Oculus, Wetzlar, Germany) were analyzed. The follow-up time was 3 months, and data comparison was made, using specific statistical analysis, with the data of 3 months postoperatively. Results: The study sample consisted of 43 eyes of 36 patients. The mean corrected visual acuity improved from 0.82 LogMAR preoperatively (SD ± 0.33) to 0.19 LogMAR (SD ± 0.13) postoperatively. The mean spherical equivalent varied from −4.63 (SD ± 3.94) preoperatively to −2.16 (SD ± 2.63) postoperatively. Asphericity varied from −0.69 (SD ± 0.32) preoperatively to −0.27 (SD ± 0.31) postoperatively. The mean maximum K was 54.01D (SD ± 3.38) preoperatively and 51.50D (SD ± 2.90) postoperatively. The mean anterior densitometric value was 18.26 (SD ± 2.03) preoperatively and 17.66 (SD ± 1.84) postoperatively. Conclusion: Corneal densitometry is an interesting technology that should be studied in keratoconus patients. Our results suggest that the corneal densitometry in the cornea’s anterior layer reduces after ICRS implantation and correlates with corneal keratometry. Further studies should be performed to increase the knowledge in this field.

Download Full-text

Outcomes of a 320-degree intrastromal corneal ring segment implantation for keratoconus: Results of a 6-month follow-up

European Journal of Ophthalmology ◽

10.1177/1120672118818018 ◽

2018 ◽

Vol 30 (1) ◽

pp. 139-146 ◽

Cited By ~ 3

Author(s):

Guilherme Andrade do Nascimento Rocha ◽

Paulo Ferrara de Almeida Cunha ◽

Leonardo Torquetti Costa ◽

Luciene Barbosa de Sousa

Keyword(s):

Visual Acuity ◽

Spherical Equivalent ◽

Distance Visual Acuity ◽

Uncorrected Distance Visual Acuity ◽

Intrastromal Corneal Ring ◽

Corrected Distance Visual Acuity ◽

Ring Segment ◽

The Mean ◽

Corneal Tomography

Importance: This study shows that a newer long-arc length intrastromal corneal ring segment is efficient and safe for keratoconus treatment. Background: To evaluate visual, tomographic results and complications of a 320-degree intrastromal corneal ring segment implantation with the femtosecond laser for keratoconus treatment. Design: A prospective, nonrandomized, and interventional study. Participants: A total of 34 eyes of 31 patients diagnosed with keratoconus were enrolled. Methods: Patients were divided into two groups based on the strategy used for 320-degree intrastromal corneal ring segment thickness selection. In one group, this selection was based on spherical equivalent (SE group) and in the other on the mean asphericity (Q group). The uncorrected and corrected distance visual acuities, spherical equivalent, K1, K2, Km, Kmax, and mean asphericity ( Q) on corneal tomography were evaluated preoperatively and at 3 and 6 months postoperatively. For astigmatism improvement, we analyzed the corneal tomographic vectorial astigmatism change preoperatively and at 6 months postoperatively. The mean follow-up period was 6.63 ± 0.96 months. Results: The mean uncorrected distance visual acuity and corrected distance visual acuity improved with a significant spherical equivalent improvement ( p < 0.05), with no differences between the 320-degree intrastromal corneal ring segment groups. All corneal tomographic parameters improved significantly ( p < 0.05) between the preoperative and postoperative intervals, with a significant better performance when we used spherical equivalent for the 320-degree intrastromal corneal ring segment thickness selection. Finally, the mean vectorial corneal tomographic astigmatism significantly improved after 6 months, again with no differences between groups. Conclusion: This study suggests that implanting a 320-degree intrastromal corneal ring segment is a safe and effective procedure for treating patients with keratoconus. It also suggests that for thickness selection spherical equivalent is the better strategy.

Download Full-text