فهرست مطالب

Current Ophthalmology - Volume:30 Issue: 2, 2018
  • Volume:30 Issue: 2, 2018
  • تاریخ انتشار: 1397/04/09
  • تعداد عناوین: 18
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  • Mohsen Bahmani Kashkouli *, Bijan Beigi Pages 99-101
  • Babak Masoomian, Jerry A. Shields, Carol L. Shields* Pages 102-109
    PurposeThe aim of this study was to review the genetics, epidemiology, clinical findings, and management of BRCA1-associated protein-1 (BAP1) cancer predisposition syndrome, particularly focusing on the development of uveal melanoma (UM).
    MethodsThis is a review article based on eligible studies identified by systematically searching PubMed, Web of Science, and reference lists.
    ResultsUM is the most common primary intraocular malignancy. Most UM cases are sporadic, but a small percentage has been documented with familial tendency. Until recently, there was little information regarding the genetics of this malignant tumor, and we have now begun to understand the pathways of development. BAP1 is a scavenger protein that regulates cell cycle, cellular differentiation, and DNA damage response. Patients and families with germline BAP1 mutation are predisposed to familial cancers including UM, mesothelioma, cutaneous melanoma (CM), renal cell carcinoma (RCC), and others. Clinicians should be aware of the implications of germline BAP1 mutation and advise genetic testing and assessment for BAP1 germline mutation in suspected patients and families.
    ConclusionsThe ability of BAP1 gene mutation to cause multiple tumor types and high penetrance in carriers suggests that this gene has an important role for influencing cancer cell growth. With progress in understanding the molecular landscape of UM and the development of treatments targeted to the pathways involving BAP1 and other gene mutations, it is possible to improve the outcome of this malignant cancer.
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    Keywords: Uveal melanoma, Mesothelioma, Renal cell carcinoma, BAP1 cancer predisposition syndrome, BRCA1-associated protein-1, BAP1
  • Mehrdad Mohammadpour, Zahra Heidari *, Hassan Hashemi Pages 110-124
    PurposeKeratoconus is a progressive disease of the cornea which can lead to blindness as irregular astigmatism increases. Currently, a variety of methods are available for the treatment of keratoconus, and in certain cases, it may be difficult to choose the most appropriate option. This article reviews available treatment modalities for keratoconus to provide the practitioner with practical and useful information for selecting the most suitable option for each individual patient.
    MethodsTo review treatment methods for different stages of keratoconus, PubMed (United States National Library of Medicine) and Scopus (Elsevier BV) databases were searched using the keywords “keratoconus”, “contact lens”, “cross-linking”, “Intacs”, “keratoplasty”, “gene therapy”, and “irregular astigmatism”, and related articles were reviewed based on disease assessment parameters and treatment methods.
    ResultsVarious methods are available for the treatment of keratoconus: eyeglasses and contact lenses in the early stages, cross-linking for stabilizing disease progression, intrastromal corneal ring segments (ICRS) for reducing refractive errors or flattening the cornea, and penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK), conductive keratoplasty, gene therapy and more recently, bowman layer transplantation (BL transplantation) in advanced stages of the disease. To achieve optimum results, it is essential to choose the best option for each individual patient.
    ConclusionsA commonality of the reviewed papers was the advancement of novel diagnostic and treatment methods in ophthalmology, which can delay the need for corneal grafting. A better understanding of keratoconus treatment options can help enhance visual rehabilitation and prevent blindness in keratoconus patients.
    Keywords: Keratoconus, Contact lens, Cross-linking, Intacs, Keratoplasty, Keraflex, Gene therapy, Bowman layer transplantation
  • Ketaki Rajurkar, Suneeta Dubey, Parmatma Prasad Gupta, Denny John, Lokesh Chauhan Pages 125-129
    PurposeThe present study aims to estimate the prevalence of non-compliance and improper drop administration technique among glaucoma patients and describe common obstacles to medication compliance.
    MethodsA hospital-based cross-sectional study, using standardized questionnaire and direct observation by study personnel was conducted among glaucoma patients aged 18 years and above at a tertiary care charitable eye hospital in North India. 151 consecutive glaucoma patients on medical therapy following up at the glaucoma clinics for at least 6 months were recruited. Non-compliance was defined as missing at-least one drop of medication per week and (or) the inability to accurately describe the medication regimen. Study personnel also assessed drop administration technique during application of eye drops by patients treating ophthalmologist-provided information, including measures of disease stability. Factors such as socioeconomic status, presence of caregiver, and number of medications with their effect on compliance were studied using chi-square statistics.
    ResultsAmong 151 patients interviewed, around 49% of patients reported problems in using glaucoma medications, with 16% of them reporting total non-compliance. 35% of patients demonstrated improper drop administration technique. Forgetfulness was cited as the main reason for being non-compliant and had a significant association with non-compliance (P = 0.00). Paying patients were more compliant as compared to subsidized patients (P = 0.05). Disease was more stable in compliant patients compared to non-compliant patients (P = 0.05). No other factor had significant association with compliance (P > 0.05).
    ConclusionsOver 50% of the patients surveyed were non-compliant, and 35% demonstrated improper administration technique. Glaucoma patients should be educated on the importance of compliance and aids that minimize forgetfulness, and delivery systems facilitating the delivery of medications to the eye could be considered to enhance patient adherence.
    Keywords: Adherence, Glaucoma, Medication, North India
  • Saeed Shokoohi-Rad, Ramin Daneshvar, Mahsa Jafarian-Shahri *, Parisa Rajaee Pages 130-135
    PurposeThe aim of this study was to compare the ocular hypertensive effect of the commercially available Betamethasone, Fluorometholone in Iran and Loteprednol Etabonate in patients undergoing keratorefractive surgery.
    MethodsIn this prospective randomized clinical trial, 300 eyes of 150 patients were included, and patients were randomly assigned to 3 groups and used one of the 3 steroid drops (Betamethasone 0.1%, Fluorometholone 0.1%, and Loteprednol Etabonate 0.5%) after myopic photorefractive keratectomy (PRK). Intraocular pressure (IOP) was measured 2, 4, and 6 weeks post-surgery. Twenty-two mmHg was set as the threshold IOP for starting anti-glaucoma medication and tapering steroid drops.
    ResultsOf 300 eyes from 150 patients over the first 6 postoperative weeks, 2 eyes in Fluorometholone group (2%), 12 eyes in Betamethasone group (12%), and 16 eyes in Loteprednol group (16%) had IOP equal or more than 22 mmHg. Analysis of variance (ANOVA) test showed that the rise in IOP was significantly different between groups in the 2nd and 4th (P ≤ 0.001) postoperative weeks but not at 6th week (P = 0.230). An IOP rise equal or more than 10 mmHg was detected in 13 and 15 eyes in Betamethasone and Loteprednol groups, respectively. None of the eyes in Fluorometholone group had such an IOP rise.
    ConclusionsLoteprednol and Fluorometholone were associated with the most and least increase in IOP, respectively. The highest pressures were detected 4 weeks after surgery in the Betamethasone and Loteprednol groups and 6 weeks after surgery in the Fluorometholone group. Fluorometholone was the safest among the three examined steroid drops in terms of IOP rise.
    Keywords: Steroid induced glaucoma, Loteprednol etabonate, Keratorefractive surgery, Photorefractive keratectomy
  • Seyed Javad Hashemian, Hosein Farrokhi, Alireza Foroutan, Mohammad Ebrahim Jafari, Mahsa Sadat Hashemian Pages 136-141
    PurposeTo investigate the changes in higher-order aberrations (HOAs) induced by the implantation of implantable collamer lenses (ICLs) and Toric ICL (TICL) in eyes with high myopia and high myopic astigmatism.
    MethodsWe investigated 33 eyes of 18 consecutive patients (in a prospective, interventional case series study), with spherical equivalent errors of −6.00 to −21.09 diopters (D) and cylindrical errors of −0.5 to −4.75 D, who underwent ICL and TICL implantation. Before and after 5 days, 2 and 6 months of surgery, the uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), defocus and adverse events of the surgery were assessed. Ocular HOAs were also evaluated by Hartmann-Shack aberrometry (Technolas PV, Rochester, New York, USA) before and after 6 months of surgery.
    ResultsAt 6.0 months after surgery, the UCVA and BCVA in 40% and 66.7% of eyes were 20/20, respectively. Mean defocus refraction and astigmatism was reduced to −0.66 and 0.65 D from −12.79 and 2.18 at baseline, respectively. For a 6 mm pupil, HOAs were not significantly changed, merely from 0.417 ± 0.162 μ before surgery to 0.393 ± 0.119 μ after surgery (P = 0.45). Spherical aberration (Z400) increased significantly (P = 00.0). Surgical induced astigmatism was lower than 0.25 D, and there were no changes in trefoils and coma aberration. No vision-threatening complications occurred during the observation period.
    ConclusionThis study shows that the ICL and TICL performed well in correcting high myopic astigmatism without significant changes in HOAs during a 6-month observation period, although the spherical aberration (Z400) increased significantly.
    Keywords: Implantable collamer lens, Higher-order aberrations, Phakic intraocular lens, Myopic astigmatism
  • Masoumeh Mohebbi, Firoozeh Rahimi, Mohammad Naser Hashemian, Mohammad Ali Zare, Ahmad Masoumi Pages 142-146
    PurposeTo investigate the impact of venting incisions on the adherence of graft to the recipient's stroma in Descemet's stripping automated endothelial keratoplasty (DSAEK).
    MethodsFifty-six patients were enrolled in this study. Patients were randomly allocated into two groups. Twenty-eight patients had a DSAEK procedure with venting incisions. The second group was treated by conventional DSAEK with no venting incisions. Slit-lamp examination and anterior segment optical coherence tomography (AS-OCT) were performed in day one and 14 days after surgery to investigate graft attachment. The thickness of cornea and lenticle were also evaluated by AS-OCT. BCVA (logMAR) was measured the day before the surgery and 14 days postoperatively.
    ResultsSubclinical graft detachment in the first day after surgery was significantly lower in patients who had a DSAEK procedure and venting incisions (P = 0.02), but no difference was noted in the rate of clinical graft detachment on day one (P = 0.24) and subclinical and clinical graft detachment on day 14 (P = 0.24, P = 0.50, respectively). The thickness of the cornea and lenticle after the surgery were statistically similar between the two groups (P = 0.903, P = 0.402, respectively). No difference in the improvement of BCVA was observed between the venting and non-venting group (P = 0.143).
    ConclusionsRoutine use of venting incisions may not be necessary in the standard DSAEK procedures. More studies with larger sample sizes are needed to better confirm the results of this study.
    Keywords: DSAEK, Graft attachment, Venting incisions
  • Samira Heydarian, Hassan Hashemi, Fereshteh Shokrollahzadeh, Abbas Ali Yekta *, Mehdi Khabazkhoob Pages 147-151
    PurposeThe aim of this study was to determine the distribution of corneal eccentricity (E-value) in a normal population and to examine related factors.
    MethodsIn this cross-sectional study, two villages were selected in Iran using multistage cluster sampling. Selected persons were invited to have a comprehensive eye examination. Examinations in each village were performed at a specific location under standard conditions. After testing for vision and refraction and conducting the slit-lamp exam, E-value was measured with Pentacam.
    ResultsOf the 3851 selected individuals, 3314 participated in the study. After applying the exclusion criteria, data from 2610 subjects was used in the analysis for this report. Mean E-value was 0.53 [95% confidence interval (CI): 0.52 to 0.54]. E-value was not significantly different between males and females. Mean E-value reduced with age from 0.60 in subjects aged 6–20 years to 0.47 in subjects older than 70 years. The hyperopic group of participants had significantly lower E-value than myopic and emmetropic ones (P ConclusionsThe results of this study showed that the cornea in normal populations is prolate, and the degree of prolateness varies by age, such that older age is associated with a less prolate cornea. This study showed that factors such as age and refractive errors and anterior chamber indices influence the E-value.
    Keywords: Corneal eccentricity, Distribution, Cross sectional study, Determinants
  • Hamidreza Torabi, Seyed-Ali Tabatabai, Alireza Khodabande Pages 152-155
    PurposeTo evaluate the treatment outcomes of patients with post cataract surgery endophthalmitis in our tertiary referral center.
    MethodsIn this prospective study, patients with presumed post cataract surgery endophthalmitis were treated based on the modified endophthalmitis vitrectomy study (EVS) guidelines and followed for at least three months. Visual and anatomical outcomes were assessed in the last follow-up visit.
    ResultsA total of 46 eyes with presumed post cataract surgery endophthalmitis were admitted to our hospital, of which 3 eyes with initial visual acuity of no light perception (NLP) and severe inflammation underwent primary evisceration. Forty-three patients were included to this study and followed up for at least three months. Culture results were positive in 51.2% of cases and streptococcus viridans was the most frequent isolated organism. Pars plana vitrectomy was performed in 16 eyes as primary treatment, and intravitreal antibiotic injection was done in 27 eyes. Re-treatment with pars plana vitrectomy was required in 15 eyes (34.9%). Best corrected visual acuity (BCVA) at final visit was 20/40 or better in 12 eyes (27.9%), between 20/200 to 20/40 in 17 eyes (39.5%), and worse than 20/200 in 14 eyes (32.6%). Evisceration was done in one eye (2.3%), and retinal detachment happened in 4 eyes (9.3%).
    ConclusionsThe visual outcomes of post cataract surgery endophthalmitis are generally poor. Our results in this study were comparable with many previous studies from other referral centers, however, unlike many reports, streptococcus viridans was the most common isolate in our study.
    Keywords: Endophthalmitis, Cataract surgery, Phacoemulsification, Vitrectomy, Intravitreal antibiotic
  • Felix Rommel *, Fynn Siegfried, Maximilian Kurz, Max Philipp Brinkmann, Mahdy Ranjbar Pages 156-160
    PurposeTo evaluate the impact of correct anatomical slab segmentation on foveal avascular zone (FAZ) dimensions in the superficial capillary plexus (SCP) and deep capillary plexus (DCP) using optical coherence tomography angiography (OCTA).
    MethodsParticipants with healthy retinas were recruited, and 5 × 5 mm OCTA images were acquired using the Canon HS-100 Angio eXpert module. FAZ size was measured in automatically (AS, manufacturer-based) and manually (MS, anatomical-based) segmented OCTA slabs by two experienced graders. FAZ dimensions, inter-rater agreement, and correlation to demographic and retinal parameters were evaluated.
    ResultsA total of 38 eyes from 20 healthy adult subjects were included in this cross-sectional study. While in AS slabs, the FAZ in the SCP was smaller than in the DCP, in MS images, it was the opposite. MS had a relevant impact on inter-rater agreement of FAZ measurements in the SCP. The FAZ area in both plexus correlated inversely with the central retinal thickness (CRT), irrespective of the segmentation applied. Furthermore, an enlargement of FAZ size in the DCP with increasing age was found. Finally, the FAZ in female participants was significantly larger than in their male counterparts, regardless of the evaluated plexus and chosen segmentation.
    ConclusionsCorrect anatomical slab segmentation has a significant impact on FAZ size measurements. Not adjusting the segmentation boundaries represents a significant source of error for measuring FAZ area and confounds comparisons across studies as well as OCTA devices.
    Keywords: Foveal avascular zone, Optical coherence tomography, Optical coherence tomography angiography, Slab segmentation
  • Hassan Hashemi, Mehdi Khabazkhoob, Mohammad Saatchi, Hadi Ostadimoghaddam*, Abbasali Yekta Pages 161-168
    PurposeTo determine the prevalence of visual impairment and blindness and related factors in the 1- to 90-year-old urban population of Mashhad.
    MethodsIn this cross-sectional study of 1- to 90-year-old residents of Mashhad, in northeastern Iran, sampling was done through random stratified cluster sampling (120 clusters). After selecting the samples and their participation in the study, all subjects had vision testing including measurement of visual acuity and refraction, as well as examinations with the slit-lamp and ophthalmoscopy. Visual impairment (primary outcomes) was defined as a visual acuity worse than of 0.5 logMAR (20/60) in the better eye.
    ResultsOf the 4453 selected persons, 3132 (70.4%) participated in the study. The prevalence of visual impairment based on presenting vision and best-corrected vision was 3.95% (95% confidence interval [CI]: 3.13–4.77) and 2.23 (95% CI: 1.54–2.91), respectively. The prevalence of presenting visual impairment increased from 1.59% in children under 5 years of age to 43.59% in people older than 65 years of age; these figures were respectively 1.59% and 42.31% based on corrected visual acuity. In the logistic regression model, older age (OR = 1.06, 95% CI: 1.04–1.07, P ConclusionsAccording to our findings, the prevalence of visual impairment was intermediate in comparison with other studies. The prevalence of visual impairment in our study was similar to the global average; however, it was markedly high at older ages. Nonetheless, refractive errors and cataracts remain as the main causes of impaired vision and blindness in this population, while these two conditions are easily treatable with correction or surgery.
    Keywords: Visual impairment, Blindness, Low-vision, Cross-sectional study, Middle-East
  • Mehryar Ray Taban* Pages 169-173
    PurposeOrbital decompression and lower eyelid retraction surgery are traditionally performed separately in staged fashion, which may be unnecessary. Herein, we evaluate the safety and efficacy of combined orbital decompression and lower eyelid retraction surgery.
    MethodsRetrospective analysis of patients undergoing combined orbital decompression and lower eyelid retraction surgery in patients with or without Graves orbitopathy, by one surgeon from 2016 to 2017. Patients with previous orbital or lower eyelid surgery were excluded. Surgical technique for orbital decompression included eyelid crease lateral-wall decompression, transconjunctival inferolateral-wall decompression, or transcaruncular medial-wall decompression, or combination. Surgical technique for lower eyelid retraction surgery described previously. Analysis included 34 surgeries (19 patients). Preoperative and postoperative photographs at longest follow-up visit were standardized and analyzed.
    ResultsEtiologies of lower eyelid retraction included thyroid eye disease (13 patients) and inherited (6 patients). Etiologies of proptosis included thyroid eye disease (13 patients) and inherited with shallow orbits and/or poor maxilla (6 patients). All 34 eyelids demonstrated improvement of lower eyelid position. The mean improvement of marginal reflex distance was 2.4 mm (range, 1.7–2.9 mm). There was one case of mild overcorrection and once case of prolonged chemosis. The average follow-up was 9 months (range, 6 months to 1 year).
    ConclusionsThis study demonstrates improvement of lower lid position in patients undergoing simultaneous orbital decompression and correction of lower eyelid retraction, irrespective of the etiology of lower eyelid retraction and proptosis or orbital decompression technique. Combined procedures may reduce the number of total procedures, patient anxiety, recovery time, and costs, without compromising the results.
    Keywords: Eyelid retraction surgery, Orbital decompression, Thyroid eye disease, Proptosis, Sclera show
  • Mehrdad Mohammadpour *, Hamid Riazi-Esfahani Pages 174-176
    PurposeTo report a case of transient visual loss following uncomplicated cataract surgery with unpreserved intracameral lidocaine.
    MethodsA 61-year-old woman with nuclear sclerosis cataract underwent uncomplicated phacoemulsification and in-the-bag intraocular lens (IOL) implantation.
    ResultsAfter opening the eye patch on the first postoperative day, the patient complained of complete blindness. Her vision was no light perception (NLP) and the Marcus-Gunn was found to be 4. Eight hours later, the patient's visual acuity improved to count fingers at 1 m. After two days, the vision improved surprisingly to 20/20 without any Marcus-Gunn. After 4 weeks, the vision decreased surprisingly to 20/80 without any Marcus-Gunn. On this day, macular optical coherence tomography (OCT) was performed, and cystoid macular edema was detected.
    ConclusionTransient visual loss after intracameral lidocaine has been reported after violation of posterior capsule during cataract surgery, and here, we report a case of transient visual loss despite uncomplicated cataract surgery.
    Keywords: Intracameral lidocaine, Transient visual loss, Macular edema
  • Majid Abrishami, Humain Baharvahdat, Seyedehmaryam Hosseini, Babak Ganjeifar * Pages 177-181
    PurposeTo describe a case of endovascular occlusion of an unruptured anterior communicating artery aneurysm presenting with acute altitudinal visual field defect is presented here.
    MethodsA 52-year-old man was evaluated and treated for altitudinal visual field defect in the right eye.
    ResultsIn ophthalmic and neuro-imaging, an accompanying anterior communication artery aneurysm was detected as a cause of visual field defect. He underwent endovascular procedure, yielding excellent outcome as full recovery of visual field defect was observed one month following the procedure and sustained when followed at month 24.
    ConclusionsVisual dysfunction is a rare presentation of unruptured anterior communication artery aneurysm. Endovascular procedure may be a safe treatment in these cases.
    Keywords: Intracranial aneurysm, Anterior communicating artery, Visual field, Endovascular procedure
  • Mohammad Taher Rajabi, Saeed Mohammadi, Narges Hassanpoor *, Seyedeh Simindokht Hosseini, Mohammad Bagher Rajabi Pages 182-185
    PurposeTo report a rare case of orbital alveolar echinococcosis in Iran.
    MethodsA 23-year-old woman with multi-lobular mass lesion in the right orbit underwent excisional biopsy via a deep lateral orbitotomy approach. The pathologic investigation of the lesion was a multilobulated cystic lesion shown where the cyst wall structure was compatible with alveolar Hydatid cyst in histopathology. Clinical course, surgical, and medical management of the disease is noted briefly in the case of orbital involvement of the alveolar echinococcosis.
    ResultsPatient was treated with anti-fungal medication, and the cysts were successfully removed by a surgical excision.
    ConclusionAlthough orbital alveolar echinococcosis is extremely rare, it is noteworthy to study its clinical manifestations and radiological examinations to be able to make a true diagnosis.
    Keywords: Orbit, Echinococcosis, Alveolar, Hydatid cyst
  • Kemal Tekin*, Mustafa Koc Page 186
    Dear Editor
    We congratulate Sedaghat et al.1 for their study entitled 'Corneal hysteresis and corneal resistance factor in pellucid marginal degeneration'. We read the article with interest. They evaluated and compared corneal hysteresis (CH) and corneal resistance factor (CRF) in pellucid marginal degeneration (PMD), keratoconus, and healthy eyes using the Ocular Response Analyzer. Their retrospective study included 102 patients with PMD, 202 patients with keratoconus, and 208 normal subjects. They found statistically significant differences in terms of CH and CRF values between the groups. We express our gratitude to the authors regarding this study. However, we want to specify some matters and our thoughts related to this article.
    As mentioned in the article, true PMD is a very rare disease. Since the similar sagittal topographic features, inferior keratoconus is generally confused with PMD. A significant number of PMD cases reported in the literature actually have corneal topographies compatible with inferior keratoconus. Many other reports purporting treatment modalities for PMD fail to show clear evidence supporting the diagnosis of PMD. These eyes do not show the classic band-like inferior thinning that is best demonstrated by a full-coverage (12 mm) corneal thickness map.2, 3 Lee et al.4 reviewed 40 eyes of 26 patients exhibiting the classic claw pattern on anterior curvature from 3993 Orbscan II records. Of these, only 9 eyes of 6 patients met their criteria for true PMD. In a recent study by us,5 we analyzed the topographic records of 2751 patients with corneal ectasia. A crab claw pattern on corneal topography was observed in 47 eyes of 32 patients. When the medical records of these patients were examined, PMD was detected in only 11 eyes of eight patients, and inferior keratoconus was detected in 36 eyes of 24 patients. We would like to ask the authors whether their 102 PMD patients are really true PMD or PMD suspect with crab claw pattern. Further, it should be remembered that corneal topography systems usually evaluate the 9 mm central part of the cornea, and in 45% of the patients with PMD, the thinnest region of the cornea was found to be outside of the 9 mm.6 Therefore, the thinnest corneal thickness values and their coordinates presented in topography systems may not reflect actual values. Accordingly, did the authors evaluate the 9 mm central zone or full pachymetric map (in the 12 mm corneal area)? Additionally, we think that it would be better to compare the CH and CRF values of PMD with inferior keratoconus cases showing crab claw pattern on corneal topography instead of keratoconus cases.
  • Mohammad Reza Sedaghat, Mahmoud Jabbarvand, Farshad Askarizadeh, Hadi Ostadimoghaddam, Foroozan Narooie-Noori * Page 187
    Reply
    We would like to thank Drs Tekin and Koc for their letter and interest in our study.1 Koc and associates point out certain similarities between pellucid marginal degeneration (PMD) and inferior keratoconus. As they stated, PMD is a rare condition, and diagnosis of PMD based on topography needs full pachymetry map. We congratulate the authors for their work, and we acknowledge their important insights on the PMD and inferior keratoconus.2 However, our study was performed before their publication, and the prevalence of PMD was not the main focus of our study. Also, we conducted this study in a tertiary referral eye clinic.
    Notably, we would like to direct Drs Tekin and Koc to the method of our retrospective study.1 We described in the method of our article that in addition to clinical manifestations and topographic/tomographic maps (sagittal and pachymetry maps), reliable diagnosis of PMD was made by an experienced corneal refractive surgeon based on the results of slit-lamp biomicroscopy (a clear thinning band in the inferior corneal peripheral zone separated from the corresponding limbus by a 1–2 mm clear zone).3, 4 It should be mentioned that PMD is defined mainly based on the biomicroscopic manifestations.3 Also, we know that the crab claw pattern on corneal topography is not a typical and classical key for PMD diagnosis.2, 5
    Additionally, Drs Tekin and Koc think that it would be better to compare the corneal hysteresis (CH) and corneal resistance factor (CRF) values of PMD with inferior keratoconus cases showing crab claw pattern on corneal topography instead of keratoconus cases. We agree with Dr. Koc, however, this is not the main focus of our study and needs another study design. Although PMD is localized as an inferior condition, our study has revealed that PMD can change central corneal biomechanical properties in terms of CH and CRF. Also, several studies have assessed the changes in the central corneal biomechanical properties (CH and CRF) in different ocular conditions with normal corneal thickness.6 A finding of note in the present study is that PMD is not a localized condition.
  • Mohsen Bahmani Kashkouli *, Parya Abdolalizadeh, Navid Abolfathzadeh, Hamed Sianati, Yasaman Hadi Pages 188-189