|Year : 2021 | Volume
| Issue : 1 | Page : 3-8
Evaluation of ocular manifestations of patients with pathological myopia at a tertiary eye care institute in Western India
Kinjal Trivedi, Charmi Madhani, Aditi Kondapurkar, Somesh Aggarwal
Department of Retina, M and J Western Regional Institute of Ophthalmology, Ahmedabad, Gujarat, India
|Date of Submission||30-Aug-2020|
|Date of Decision||31-Oct-2020|
|Date of Acceptance||02-Feb-2021|
|Date of Web Publication||02-Jul-2021|
B/102, Anand Milan Towers, Near Municipal Garden, Shahibaug, Ahmedabad - 380 004, Gujarat
Source of Support: None, Conflict of Interest: None
Introduction: Pathological myopia (PM) is defined as a refractive error ≥(−6) D or an axial length >26 mm causing complications such as early nuclear sclerosis, zonular dehiscence, macular hole, lacquer cracks, Forster-Fuchs spots, myopic traction maculopathy, macular choroidal neovascularization, and peripheral degenerations predisposing to rhegmatogenous retinal detachment (RRD).
Materials and Methodology: In this cross-sectional observational study, we have studied 106 eyes of 56 patients. After history and examination, axial length was measured using A-scan biometry. Patients having myopic maculopathy underwent optical coherence tomography and fundus fluorescein angiography and were treated appropriately. The data were entered into Microsoft Excel sheet for statistical analysis.
Results: Incidence of high myopia was maximum in 21–30 years (36%). Eighteen percent had positive family history, and in 89%, the presentation was bilateral. About 43.39% eyes had refraction value in the range of −6 to −10 D and 70.75% eyes had axial length between 26 and 30 mm. Nearly 39.62% eyes had best-corrected visual acuity in the range of 6/18–6/36. Fifty-two percent eyes had some vitreous degeneration. Myopic choroidal neovascular membrane (CNVM) was seen in 4.71% eyes. Lattice degeneration was the most common (43.39%) lesion predisposing to RD, majority seen in superotemporal quadrant (63.04%). Incidence of RRD was 6.52% and 15% in eyes with refractive error less than and more than −10 D, respectively.
Conclusion: PM can cause irreversible vision loss with its complications such as CNVM and RRD. Awareness among myopic population regarding visual hygiene, safety precautions, risks, and complications involved can detect complications at the earliest helping in retaining useful ocular function.
Keywords: Lattice degeneration, myopic choroidal neovascular membrane, myopic maculopathy, pathological myopia, rhegmatogenous retinal detachment
|How to cite this article:|
Trivedi K, Madhani C, Kondapurkar A, Aggarwal S. Evaluation of ocular manifestations of patients with pathological myopia at a tertiary eye care institute in Western India. J Curr Res Sci Med 2021;7:3-8
|How to cite this URL:|
Trivedi K, Madhani C, Kondapurkar A, Aggarwal S. Evaluation of ocular manifestations of patients with pathological myopia at a tertiary eye care institute in Western India. J Curr Res Sci Med [serial online] 2021 [cited 2021 Dec 4];7:3-8. Available from: https://www.jcrsmed.org/text.asp?2021/7/1/3/320504
| Introduction|| |
Myopia is a significant global public health and socioeconomic problem, especially in Asian countries. Myopia occurs due to the elongation of the axial length, causing the light rays to focus in front of the retina. It is defined as a refractive error of ≥(−0.5) diopters (D).
One way of classifying myopia is nonsyndromic myopia and syndromic myopia. It can also be classified as Physiological myopia (usually low-grade myopia) and pathological myopia (PM). PM is defined as a refractive error ≥(−6) D or an axial length >26 mm. According to a recent consensus article by Ohno-Matsui et al., PM was defined by myopic chorioretinal atrophy equal to or more serious than diffuse atrophy (by meta-analysis for PM [META-PM] study group classification) and/or the presence of posterior staphylomas.
Myopia is a highly heritable trait, and genome-wide association studies have revealed some of the loci involved. Public policy to increase outdoor activity in school-going children, orthokeratology and contact lenses, glasses, and pharmacologic intervention in the form of low-dose atropine form the main thrusts of the fight against myopia.
Challenges of PM are early nuclear sclerosis, zonular dehiscence causing lens subluxation, and complications during cataract surgery. Peripheral retinal pathologies predisposing to rhegmatogenous retinal detachment are also commonly seen. Macular complications such as myopic foveoschisis and macular hole, lacquer cracks, Forster-Fuchs spots, myopic traction maculopathy, and macular choroidal neovascularization can be present. Myopia can be associated with primary open-angle glaucoma, tilted disc, and peripapillary atrophy. The common causes of blindness in patients with PM include foveoschisis, glaucoma-like optic neuropathy, and most importantly myopic choroidal neovascular membrane (CNVM) which can be treated with antivascular endothelial growth factor therapy if detected early.,,,
Myopia can lead to significant visual morbidity and irreversible blindness in young age. The objectives of this study are to analyze the spectrum of ocular manifestations in patients of PM presenting at our tertiary care center and also find possible association between their axial length, refractive correction, and their presenting best-corrected visual acuity (BCVA). Results and conclusions of this study shall help in anticipating and in turn diagnosing early the complications of PM which will improve visual prognosis of these patients. We also wish to increase awareness of regular periodic fundus examinations by this study, not only in the patient but also in their families due to the presence of strong family history in it.
| Materials and Methodology|| |
Ethical measures were adhered to throughout all phases of the research. The study was conducted among patients attending our tertiary health-care referral center, who were diagnosed with PM and either patients or their guardians were willing to participate in the study. We have included patients above the age of 5 years presenting with axial type of PM. The duration of the study was from July 2019 to February 2020. Patients with all other types of myopia including congenital myopia and high myopia associated with any systemic disorder were excluded from the study based on clinical examination and the history given by them or guardians. Patients in whom any prior intervention for high myopia-related pathologies had been done, those with other preexisting ocular conditions unrelated to PM and those with any media opacity precluding posterior segment examination clinically were excluded from the study.
Sample size calculation: n = ( z2p [1-p])/d2, where z = considering that the values are normally distributed, 95% of the values will fall within 2 standard errors of the mean. The value of z corresponding to this is 1.96 (from the standard normal variate tables). P = prevalence of high myopia in the population of the actual study. This value was found to be 3.6% from a pilot study done at our tertiary care center data of which is not included in statistical analysis of actual study. This prevalence also correlates with other studies on PM.
1-p = 100-p; 100-3.6 = 96.4 in our study.
d = precision of the study; this is taken 5% in our study.
After putting all the values in the equation, the sample size for our study was calculated to be 55 eyes.
This is a cross-sectional observational study with sample size of 106 eyes of 56 patients. Informed consent was obtained from all the respondents before enrolling in the study.
A thorough history followed by examination was done of each patient. Ocular examination comprised BCVA, slit-lamp examination including intraocular pressure (IOP) measurement by noncontact tonometry followed by posterior segment examination. Refraction was performed in all patients. We uniformly used combination eye drop having tropicamide 0.8% w/v with phenylephrine and 5% w/v for fundus examination. The axial length was measured using A-scan biometry and keratometry was done. Those with abnormal K-reading were excluded from the study. Those with posterior staphyloma were confirmed with B scan.
Patients having myopic maculopathy and peripheral retinal degenerations were treated appropriately. The data was entered into Microsoft Excel sheet for statistical analysis. Percentage values were calculated wherever applicable.
| Results|| |
The study included 106 eyes of 56 patients out of which 30 (53.57%) were male and rest 26 (46.42%) were female. Age of the patients was in the range of 7–52 years. Incidence of high myopia was found to be maximum in 21–30 years age group which had 20 (36%) patients followed closely by age group of 11–20 years age which had 19 (34%) patients [Table 1]. In our study, majority 30 (53.57%) of the patients were students by occupation followed by homemakers (10 patients – 17.85%) [Table 2]. Ten patients (18%) had positive family history of myopic refractive error. Of 56 patients of PM, only 6 (11%) patients had unilateral occurrence.
Of 106 eyes of 56 patients, majority of 46 (43.39%) eyes had refraction value falling in the range of − 6 to − 10 D followed by 38 (35.84%) eyes with value in the range of − 10 to − 14 D of myopia [Table 3]. Maximum 75 (70.75%) eyes had axial length between 26 and 30 mm. Only 9 (8.49%) eyes had axial length >32 mm. In our study, maximum 42 (39.62%) eyes had BCVA in the range of 6/18–6/36 on Snellen chart. This range was closely followed by 6/36–6/60 range and 6/6–6/18 range which had 30 (28.30%) and 23 (21.69%) eyes, respectively. BCVA was inversely correlated with higher refractive errors and higher axial lengths.
|Table 3: Analysis of study population based on refractive status in diopters|
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In our study, of 106 eyes, only 8 (7.54%) eyes had increased IOP in the range of 21–26 mm Hg, and complete glaucoma evaluation was performed and managed accordingly. Rest 98 (92.45%) eyes had their IOPs within the normal range.
Of 106 eyes, 55 (52%) eyes had some vitreous pathology at the presentation. 5 eyes had both vitreous fibrillations with strands and posterior vitreous detachment (PVD). 30 eyes had PVD and 20 eyes had only vitreous strands and fibrillations.
In our study, chorioretinal atrophic patches, temporal crescent, and peripapillary atrophy were among the most common posterior pole pathologies associated with high myopia which were present in, respectively, 49 (46.22%), 45 (42.45%), and 41 (38.67%) eyes. Sight-threatening changes such as myopic CNVM were present in 5 (4.71%) eyes [Table 4].
|Table 4: Posterior pole changes in pathological myopia in our study population|
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Among eyes having lesions predisposing to RD, the most common lesions were lattice degeneration (43.39%) and retinal tears (19.81%) which were managed and followed up appropriately [Table 5].
|Table 5: Peripheral retinal degenerations in high myopic patients predisposing to retinal detachment|
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In our study, 46 (43.39%) eyes out of 106 eyes had lattice degeneration. Many eyes had lattice degenerations in multiple quadrants which are counted as individual responses to get a collective idea regarding quadrant-wise distribution of the lesion. Superotemporal quadrant had maximum number of lattice degenerations (63.04%).
Among eyes with lesions not predisposing to RD, tigroid fundus (63.20%) and paving-stone degeneration (32.07%) were most commonly encountered in our study population. Out of 106 eyes, only 39 (36.79%) eyes had associated ocular pathologies which included retinitis pigmentosa (6.60%), nuclear sclerotic cataract (20.75%), posterior subcapsular cataract (11.32%), primary open-angle glaucoma (7.54%), and strabismus (1.88%).
In our study, we found rhegmatogenous retinal detachment (RRD) as a presenting feature of PM in 3 (6.52%) eyes out of 46 eyes with <−10 D refractive error. This figure was 15% (9 eyes out of 60 eyes) in eyes with refractive error more than − 10 D, which was more than double in comparison.
The association of BCVA with different retinal pathologies is summarized in [Table 6].
|Table 6: Analysis of distribution of best-corrected visual acuity in study population and its association with different retinal pathologies|
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| Discussion|| |
We studied 106 eyes of 56 patients with PM, of which its prevalence was most common between the age group 21 and 30 years followed by age group 11 and 20 years. The prevalence decreased drastically with increasing age. Only 2 (3.5%) patients with age >50 years were affected by the condition in our study population. This correlates well with Framingham Offspring Eye Study Group which was a cross-sectional study conducted on the offsprings of the Framingham Eye Study cohort with sample size of 1585 persons. Their results also reflected that the prevalence of myopia decreased with increasing age, from about 60% for ages 23–34 years to about 20% for ages 65 years and older.
Out of 56 patients in our study, 30 (53.57%) were males and rest 26 (46.42%) were females. More males presenting to our institute might be due to social factors resulting in more awareness in male population. Only 18% of cases had family history of myopia. This might be due to less awareness leading to lower reporting among the low socioeconomic group. Majority of patients in this study were from student community which suggests that those people due to higher education are more aware of their refractive error and seek ophthalmic opinion earlier.
Out of 56 patients of PM, 50 had bilateral presentation and only 6 patients had unilateral occurrence. In cases of unilateral myopia, good prognosis for monocular visual acuity as well as binocular vision is expected if timely and consistent therapy is administered.
Majority 84 (79.24%) eyes fell into the dioptric range of − 6 to − 14 D. Out of 106 eyes, even after full correction with glasses, majority of them (42 eyes – 39.62%) had BCVA improving only up to the range of 6/18–6/36 on Snellen chart. This indicates that extreme degrees of myopia are relatively less frequent and greater the refractive error is lesser the BCVA. Majority of eyes (75 eyes – 70.75%) had axial length between 26 and 30 mm which shows that axial elongation of the eye ball is the main component causing myopic progression.
The Blue Mountains Eye Study has successfully confirmed a positive correlation between glaucoma and myopia. This correlation was stronger for eyes with moderate-to-high myopia with odds ratio (OR) 3.3 and 95% confidence intervals (CIs) of 1.7–6.4. Glaucoma was found to be present in 4.4% eyes with moderate-to-high myopia versus in 1.5% eyes with no myopia. They concluded that myopic patients had two- to three-fold increased risk of glaucoma independent of other glaucoma risk factors and IOP. On the similar line, in our study population, 8 (7.54%) eyes had increased IOP and glaucomatous disc changes in the range of 21–26 mmHg. This correlates well with the findings of the Blue Mountains Eye study suggesting higher prevalence of glaucoma in myopic population.
The Blue Mountains Eye Study also proved statistically significant association between high myopia and nuclear cataract (OR: 3.3 and 95% CI: 1.5–7.4). Incident posterior subcapsular cataract was also associated with moderate-to-high myopia (OR: 4.4 and 95% CI: 1.7–11.5), after adjustment for multiple potential confounders, including the severity of nuclear opacity. Incident cataract surgery was also significantly associated with myopia. This correlates well with the findings of our study. In our study, of 106 eyes, 22 (20.75%) eyes had associated nuclear sclerotic cataract and 12 (11.32%) eyes had posterior subcapsular cataract. This suggests overall higher incidence of cataract formation in high myopic population.
In one study done by Hayashi K, 600 eyes of 600 patients were studied for PVD status using swept-source optical coherence tomography. The PVD stage was significantly greater in the high myopia group than in the nonhigh myopia group in all age categories (P ≤ 0.0395). Abnormal PVD characteristics of pathologic myopia were detected in 1.7% of eyes in the high myopia group. This study concluded, using age- and sex-matched patients, that partial and complete PVD develop at a significantly younger age in highly myopic eyes compared with nonhighly myopic eyes, suggesting that PVD-related retinal pathologies occur younger in highly myopic patients. These findings resonated with our study also as more than 50% of cases in our study population had vitreous abnormalities which suggests that liquefaction of the vitreous begins at an earlier age in patients with high myopia and progresses with age and axial elongation and thus resulted in a frequent occurrence of PVD (33.01% incidence) in our study also.
Brasil OF studied 57 eyes of 37 patients with refractive error of at least − 6.00 diopters for fundus examination. They found a temporal crescent in 36.5% and a peripapillary one in 20% of the eyes. Choroidal vessels were seen in 35% of the eyes. Posterior pole changes were as follows: posterior staphyloma in 10.5%, Fuchs spots in 3.5%, and lacquer cracks in 1.5%. Peripheral retinal examination revealed paving-stone chorioretinal atrophy in 17.5%, white without pressure in 10.5%, lattice degeneration in 5%, retinal tears in 3.5%, and retinoschisis in 1.5% of the examined eyes.
Celorio JM studied 436 eyes of 218 patients with myopia of − 6.00 diopters or more in both eyes. They found that out of 218 patients, 72 (33.0%) patients had lattice degeneration of the retina.
Findings of these studies are in line with our findings. Majority of patients in our study group had chorioretinal atrophic patches (46.22%), temporal crescent (42.45%), and peripapillary atrophy (38.67%) among the most common posterior pole pathologies. This was followed by posterior staphyloma – 35.84%, macular pigmentation – 9.43%, lacquer cracks – 6.60%, myopic CNVM – 4.71%, and Forster-Fuchs spots – 3.77%. Lattice degeneration (43.39%) was the most common type of peripheral degeneration predisposing to RD in our study which is in contrast with the above studies. Among the number of lattice degeneration noted, majority of them (63.04%) were seen in the superotemporal quadrant probably due to excessive stretching and increased vascularity in this area. The prevalence of lattice degeneration is influenced by the amount of axial elongation in highly myopic eyes. Apart from lattice degeneration, peripheral retinal holes and areas with white without pressure were seen in, respectively, 19.81% and 10.37% eyes in our study.
In our study, patients with refractive status of more than 10 D showed two-fold risk of RD, showing that the risk of RD is directly proportional to the higher degrees of myopia. This was supported by findings of another study done by Kim M. They investigated the mechanism of RRD in 1599 patients based on the results of axial length distribution. The mean axial length was significantly longer in patients younger than 50 years old than that in patients ≥50 years old (26.18 ± 1.86 mm versus 24.55 ± 1.67 mm, respectively, P < 0.001). The percentage of patients with high myopia (axial length ≥26 mm) in patients <50 years old was higher than that in those ≥50 years old (51.9% vs. 15.0%, respectively, P < 0.001; OR: 6.11; 95% confidence interval: 4.83–7.74). This indicates that myopia or high myopia-induced early vitreous detachment appears to be a major mechanism of occurrence of RRD in these young patients making them more vulnerable for RRD compared to age-matched population.
Hence, this study demonstrates that the fundus findings in high myopic patients can directly lead to decreased vision if the changes are on the posterior pole and can indirectly contribute to vision loss if retinal detachment develops secondary to peripheral retinal degeneration. This information is very useful while evaluating, counseling and following up patients with high degrees of myopia.
| Conclusion|| |
PM is a complex eye disease, and degenerative changes are more commonly seen in higher degrees of myopia. All cases of myopia must be examined meticulously with indirect ophthalmoscope with scleral indentation which can pick up complications at the earliest to treat them effectively. Myopic population has to be informed about the warning signs and symptoms to report early for better management. As PM can have hereditability, these patients should also be made aware that examination of family members are mandatory. All patients with PM should be monitored periodically. Genetic counseling and low vision aids are advised whenever necessary.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]