سعید رحمنی

Background and Aims :

Blindness is one of the major health problems and diseases, such as corneal opacity, cataracts, glaucoma, and age-related macular degeneration due to diabetes are recognized as the most important causes of bilateral blindness worldwide. Among these factors, corneal diseases are considered as an important cause of blindness. The aim of this study was to review the prevalence, causative agents, treatment methods, and also the use of keratoprosthesis or artificial cornea as the last option to restore vision to blind patients with severe corneal injuries.

Methods :

Studies related to the subject were collected and reviewed using valid databases, such as PubMed and Google Scholar.

 Results :

Out of more than 1000 articles in the field of the artificial cornea, about 70 related articles were selected and reviewed.

Conclusion :

Generally, keratoprosthesis is used for patients for whom corneal transplantation is not possible or the risk of corneal transplantation rejection is high. The patient’s current condition and the outcome of the patient’s anterior and posterior segment examinations, previous treatments and surgeries, and the medications used should be considered. If a person has advanced retinal disease or glaucoma, he/she is not a good candidate for keratoprosthesis. If the patient’s vision in either eye is within the range of light perception or hand movement detection, while the optic nerve and macula are healthy, it is appropriate to use keratoprosthesis. It can be said that there is still no type of keratoprosthesis that can be used without side effects and for all patients in need, but researchers are still trying to improve the quality of keratoprostheses, which can restore patients’ lost vision with minimal complications.

Solar spectrum is composed of different wavelengths that some of them may lead to various ocular diseases. The aim of this study was to investigate the effectiveness of sunglasses in filtering harmful light.

In this cross-sectional study, 56 pairs (112 lenses) of branded sunglasses randomly collected from different importing companies. A spectrophotometer was used to measure blue light transmission. For statistical analysis, non-parametric Mann-Whitney and Kruskal-Wallis tests were used. A P ≤ 0.05 was considered statistically significant.

The mean UVA and UVB transmission of the sunglasses were 0.16±1.21% and 0.01±0.06 %, respectively. The mean blue light transmission of the sunglasses was 10.03 ± 3.91 %. The effect of different colors on the blue light transmission was significant (P≤0.001). Polarization and visible light transmission of the sunglasses had no significant effect on blue light transmission (P=0.3).

The effectiveness of available sunglasses to filter hazardous light was acceptable, and brown colored sunglasses was the best option to filter of the blue light.

Ocular thyroid disease is a common complication associated with Graveschr('39') disease and hyperthyroidism, which in severe cases there is a risk of irreversible loss of vision. The aim of this study was to compare the visual acuity, refractive errors, proptosis and ocular deviation of these patients with healthy individuals.

In this historical cohort study, 65 patients with history of thyroid disease were compared with 65 healthy subjects. Patients in the age range of 24 to 60 years with a history of thyroid disease and healthy individuals were selected from those who referred to the eye clinic who did not have thyroid disease. The proptosis of the eyes was measured with Hertel exophthalmometer. Visual acuity of the patients was measured with Snellen chart and refractive error measurement was done with an auto-refractometer.

Of the patients, 53 (81.5%) were males and 12 (18.5%) were females. Sphere refractive error in patients and healthy individuals was -0.85±2.44 diopters and -0.46±1.26 diopters, respectively. The mean visual acuity in the patient and healthy groups was 0.91±0.13 and 0.96±0.08 in Snellen unit (p≤0.0001), respectively. The mean proptosis in patient and healthy individuals was 17.7±2.55 mm and 16.05±1.86 mm (p≤0.0001), respectively. The mean of total eye astigmatism in patient and healthy individuals was -1.11±1.19 diopters and -0.6±0.66 diopters, respectively (p≤0.0001).

Higher astigmatism and proptosis and decreased visual acuity in the patients, indicating thyroid disease has affected on the involved eye.

Vision improvement and reduction of refractive errors are considered as important goals of cataract surgery. The purpose of this study was to evaluate residual refractive errors after cataract surgery in the patients with senile cataract in Shahid Rahimi Hospital in Khorramabad City between 2017 and 2018.

This cross-sectional study included 178 patients. Visual acuity, refractive errors and biometry of 192 eyes with senile cataract were evaluated before and one month after surgery. Refractive error and biometry measurements were performed with an autorefractometer and IOL master, respectively. SRK/T formula was used for IOL power calculation. We used paired T-test for analysis of data with normal distribution and non-parametric Wilcoxon test for the rest of data. P<0.05 was considered statistically significant.

The mean equivalent spherical refraction decreased from -0.7 ±0.22 before surgery to -0.04 ±0.06 after surgery (P≤0.001). Before and after surgery ,the mean values for corrected visual acuity were 0.42±0.01 D and 0.91±0.01 D (P≤0.0001) and the mean values for axial length of the eyes were 23.13±0.05 and 23.07±0.05, respectively (P≤0.001). The mean values for anterior chamber depth of the eyes was 3.07±0.02 mm before the surgery which changed to 3.73 ±0.03 mm after the surgery (P≤0.0001).  

The results showed that refractive errors (%86) after cataract surgery were within acceptable range (±1.00 D) and the best corrected visual acuity was better than 0.5

computer vision syndrome refers to a set of visual and non- visual symptoms due to long- term use of video terminals and causes complaints such as; blur vision, difficulty in vision of near and far, burning, headache, back and neck discomfort. Considering the increasing use of computers in the official environments and various jobs and the consequent increasing in clinical referrals of computer users due to eye complaints caused by working with computer, computer vision syndrome has become one of the most important health issues in society. In Iran, the most common eye problems were related to extra ocular problems with a prevalence of 46.2% and eye strain with a prevalence of 45.4% and the prevalence of eye fatigue due to working with video terminals was reported to be 91.4%. In Saudi Arabia, headaches and vision problems were reported with 68% and 65% prevalence, respectively. In Ghana, the prevalence of computer vision syndrome was 51.5%. This study was aimed to evaluate visual problems and functions in professional computer users.

This cross- sectional study was carried out on 40 professional computer users, aged between 20 and 30 years old, who used the computer at least 4 hours per day in 1397. The inclusion criteria were as follows: Age range 20 to 30 years, no amblyopia, no strabismus, no history of refractive surgery, no pathological eye diseases and systemic diseases such as diabetes, high blood pressure and MS and do not take any ophthalmic and systemic drugs that affect the eyes such as the antidepressants and antibiotics. A questionnaire was used to assess visual complications in four sections: eye strain, visual difficulty, ocular disorders and extra ocular disorders. Then visual examinations including: visual acuity in far and near distances, heterophoria measurement in far and near distances, stereoacuity, accommodation amplitude, accommodation facility and response, near point of convergence, fusional vergence, contrast sensitivity in the four spatial frequencies of  3, 6, 12 and 18 cycle per degree and tear break up time were performed. Refractive errors were measured using a Japanese-made Topcon Autokerato Refractometer (ARK-KR.8800, Topcon, Tokyo, Japan). The monocular and binocular vision was recorded with the best optical correction at a distance of 6 meters and 40 centimeters by logarithmic chart based on the Log MAR system. The deviation of cases was measured by the cover test method at a distance of 6 m and at 40 cm. To examine the accommodation amplitude, the near point of accommodation was measured using the push-up method. The accommodation response of cases was measured by Monocular Estimation Method (MEM). The near point of convergence was also measured by push-up method. The TNO random dot test was used to assess stereopsis. Fusional vergences were measured by prism bar both at a distance of 6 m and at 40 cm. To measure contrast sensitivity, the CSV-1000 Chart (VectorVision, Inc., OH, USA) was used. By measuring the tear break up time, the stability of the tear film were examined and the cases of dry eye were identified by using the slide lamp and fluorescent. For statistical analysis, descriptive statistics including concentration and dispersion criteria of SPSS 20 were used.

In this study, the mean and standard deviation of age was 26.48±2.72 and the mean and standard deviation of using computer was 5.82±0.84 hours per day (range 4 to 8 hours). According to the results, the mean visual acuity of all cases with the best optical correction was 0.0 logarithm. At a distance of 40 cm, 70% of the cases had no heterophoria and 30% of the cases had exophoria with less than 10 prism diopters. The means and standard deviations of blur, break and recovery by base out prism at 6 meter were: 11.40±3.30, 17.85±4.11 and 12.78±3.83 prism diopter respectively and at 40 centimeter were 17.59±2.76, 25.40±5.16 and 17.25±3.49 prism diopter respectively and by base in prism at 6 meters were: 0.55±1.28, 8.80±1.80 and 6.30±1.78 prism diopter respectively and at 40 centimeter were: 12.90±2.67, 19.05±3.02 and 14.05±2.77 prism diopter respectively. The means and standard deviations of stereoacuity, accommodation amplitude, accommodation facility and response, near point of convergence and tear break up time were respectively; 52.0±11.36 seconds of arc, 9.65±2.48 diopter, 10.5±3.0 cycle per minutes, 0.35±0.23 diopter, 2.85±3.37 centimeters and 7.45±3.17 seconds and the means and standard deviations of contrast sensitivity in the spatial frequencies of 3, 6, 12 and 18 cycle per degree were respectively: 1.75±0.11, 2.11±0.14, 1.86±0.13 and 1.44±0.13 log units. According to the questionnaire the most common complaints were in the ocular surface problems section with 32% and eye strain with 27%.

In this study, two important issues were discussed, one of which includes questions related to computer vision problems from the point of view of professional users and the other is the results of eye examinations of them. In the first part, based on the questionnaire the most complaints were in the section of ocular surface disorders with 32% and eye strain with 27%. In fact, long-term computer usage causes symptoms such as; Feeling dryness, burning, tearing when working with a computer and eye strain.In the second part, it was found that the contrast sensitivity at all frequencies and the accommodation amplitude were nearly decreased, and in a low percentage of people, a decrease in the accommodation facility were observed. The tear break up time was significantly decreased. Stereopsis of the cases was in the normal range and according to this study was not affected by computer work. In this study, at a distance of 6 m, heterophoria in the cases were in the normal range of exophoria, and at a distance of 40 cm, 30% of cases had small degrees of exophoria. One of the reasons for the increase in near exophoria in these people can be a decrease in the accommodation amplitude and also recede of the near point of convergence, which can cause symptoms such as fatigue, headache, blurred vision and diplopia. According to Morganchr('39')s table of normal values of fusional vergences, the fusional versions of the studied cases were in the normal range at 6 meters and 40 centimeters. In the present study, the near point of convergence of more than 5 cm was considered as a problem and statistical studies showed that 75% of users had a near point of convergence of less than 5 cm, so this study showed that the near point of convergence was not affected by working with a computer.An examination of the accommodation facility of the cases showed that the binocular accommodation facility in 35% of people was less than 10 cycles per minute. Accommodation facility helps to maintain a clear and single image while working in near distance. If accommodation facility is reduced, the flexibility to focus at a variety of viewing distances immediately after long-term use of the computer will be difficult, which can cause blurred vision and eye strain in some users.The accommodation response of cases were within the normal range of 0.5±0.25 diopter. If the accommodation response is greater than the accommodation diopter stimulation, symptoms such as blurred vision and eye fatigue were reported. This study found that, this eye function was not affected by computer use. Considering the average age of the cases, the accommodation amplitude of less than 8 diopters was considered as a decrease in the accommodation amplitude, which about 35% of people had 8 diopters or less than 8 diopters, but the mean accommodation amplitude was within normal range. Prolonged use of the computer can reduce the accommodation amplitude and cause symptoms such as fatigue and blurred vision. The exact cause of this decrease is not clear, but it seems to be more due to accommodation fatigue.In the present study, the mean contrast sensitivity decreased in all spatial frequencies. However, according to the normal values provided by Vectorvision for ages 20 to 55 years, the contrast sensitivity in the spatial frequencies of 3, 6, 12 and 18 cycles per degree were: 1.84±0.14, 2.09±0.16, 1.76±0.17 and 1.33±0.19 in the logarithmic unit respectively, the contrast sensitivity of users was within the normal range. In this study, tear break up time of more than 10 seconds was considered to be normal and less than this amount was considered as a problem in the stability of the tear film. Using a computer affects the pattern of blinking, eye level hemostasis and tear film function. In fact, reducing the rate of blinking disturbs the balance of replenishment and evaporation of the tear film. On the other hand, if the screen angle is higher than the primary gaze of viewing, this evaporation will occur more frequently, which will cause symptoms such as burning, redness and tearing in computer users. To reduce eye problems and symptoms, users can be advised to rest their eyes at regular intervals. It is also recommended that future studies use qualitative tests in addition to quantitative tests to assess the tear layer. The impact of computers and other devices such as mobile phones and tablets on the visual functions of different age groups can also be examined.

Blindness is one of the permanent physical damage that is found frequently in war survivors. In monocular blind veterans, preservation and care of the remaining eye is very important. This study aimed to investigate diseases and disorders of both eyes of monocular blind veterans. A total of 1820 monocular blind veterans from 19 provinces of Iran were surveyed between 2010 and 2016. Demographic data including age, gender, marital status, injury rate, associated injuries, educational level and employment status were collected. After examination of the veterans’ eyes, diseases of the both eyes and eyelid disorders were recorded by an ophthalmologist. Furthermore, treatment plans were provided to each patients. The mean age of 1820 participants was 45.8 ± 7.8 years. About two-thirds (73.6%) of participants had injuries other than blindness. More than half (54.2%) of the blind eyes had diseases, the most frequent of which was phthisis bulbi (11.0%). A total of 405 (22.2%) of the non-blind eyes were healthy. The frequencies of diseases in non-blind eyes were as follows: refractive error, 620 (34.1%); presbyopia, 533 (29.3%); cataract, 62 (3.4%); glaucoma, 32 (1.7%); and others, 168 (9.3%). Except for the glaucoma, these diseases were associated with age (P<0.05). Entropion (13.1%) and incomplete eyelid closure (9.8%) were the most common eyelid disorders. The majority of the blind (93.7%) and non-blind (94.3%) eyes needed follow-up in the next year of the study. In monocular blind veterans, the most frequent diseases and disorders of the blind eyes, non-blind eyes and eyelids were phthisis bulbi, refractive errors and entropion, respectively. Regarding the importance of preserving the vision of non-blind eyes and the frequency of diseases in both eyes of these veterans, periodic examination is necessary.

To evaluate the long-term stability of subjective refraction after deep anterior lamellar keratoplasty (DALK) performed in keratoconus-affected eyes. This retrospective case series analyzed the data of 73 eyes in 69 patients with keratoconus, who underwent DALK. Only patients with clear grafts, who had all sutures removed for at least 12 months, were enrolled. The corrected distance visual acuity (CDVA), spherical equivalent refraction, refractive astigmatism, and vector components of refractive astigmatism (J0 and J45) were recorded and compared at different time points after all sutures were removed. The mean age of the patients was 28.3±8.3 years at the time of keratoplasty. No significant changes in the CDVA were observed during the follow-up. Spherical equivalent refraction was measured at 1 month (23.18±3.41) and 3 months (4.29±4.26) after complete suture removal differed significantly from that measured at the last examination (4.70±3.75, respectively). These measured values were stabilized from 6 months after complete suture removal onward. Refractive astigmatism and its vector components (J0 and J45) did not change over time after complete suture removal. Refraction is stabilized 6 months after complete DALK suture removal. Therefore, postponing refractive surgery until this time is advisable to manage post-DALK refractive errors.

Bina color vision test was devleoped by a local company in Iran. There was no information available about the quality and the accuracy of this test and no decision could be made about its clinical application. In order To determine its accuracy, this test was compared with Ishihara’s Pseudo Isochromatic Plates and H16 Panel test.
The participants were selected from the previous screenings in Tehran and Ghom provinces and were referred to an optometry practice. After performing a routine eye exam, the participants were tested under the same luminance condition using Bina panel test (developed in Iran), Ishihara’s PIPs (developed in Japan), and H16 panel test (developed in UK), in random order.Similar to H16 test, the procedure for Bina test was based on the manual. Bina test was repeated 30 minutes after completion of the final test.
A total of 94 participants with no color vision defects, and 76 with color vision defect (detected by Ishihara’s PIP), with no other pathology, participated in the study. With H16, 94 individuals showed no defects, 57 were diagnosed with color vision defect, and in 19 participants the type of defect could not be diagnosed. With Bina test, 94 individuals showed no defects, 61 were diagnosed with color vision defect, and in 15 individuals the type of defect could not be diagnosed. In diagnosing the type of defect, Bina test and H 16 showed 87.9% agreement (Kappa= 0.897). In diagnosing the type of defect, Bina test showed repeatability of 72% (Kappa=0.72).
The accuracy of diagnosis of color vision defect with Bina color vision panel test is adequate.

To report an acute endophthalmitis that developed after keratoprosthesis implantation in a patient with Stevens-Johnson syndrome.
Case Report: A 61 year-old man had corneal keratinization and dry eye due to Stevens-Johnson disease. Visual acuity was light perception in both eyes. Since keratoplasty was not applicable, Pintucci type keratoprosthesis was considered for his right eye. The patient underwent a two-stage operation including surface reconstruction with mucous membrane graft and keratoprosthesis implantation. One day postoperatively, visual acuity was hand motion and the mucous membrane graft was inflammatous and sings of necrotic tissue were seen around the optical cylinder of the keratoprosthesis. Ten days postoperatively, the visual acuity was reduced to no light perception and the eye had discharge, pain and acute inflammation and the necrotic tissue was developed around the optical cylinder of keratoprosthesis. Based on the clinical findings and vitreous involvements documented by B-scan, the diagnosis of acute endophthalmitis was made and the right eye was eviscerated.
Regarding to mucous membrane graft necrosis and endophthalmitis after the keratoprosthesis implantation in this case, the risk of the complications should always be considered in patients with Stevens-Johnson syndrome.

Delay in light irradiance can improve the polymeric structure and mechanical properties of resin cement and uniform stress distribution. The aim of this study was to evaluate the effect of light activation modes (immediate, 5 and 10-minute delay) on the push-out bond strength of cemented fiber posts with two types of resin cements in different of root canal regions.
In sixty extractedsingle canal and endodontic therapied roots, FRC Postec Plus were cemented with two resin cements, Nexus3 and Panavia F2.0, in three curing methods, immediate, 5, and 10 minute delay. After 24 hours storing in a dark place, they were cut into three sections: coronal, middle and apical. The push-out bond strength test was performed using the universal testing machine. Failure modes were evaluated using stereomicroscope. Data were analyzed by ANOVA and Tukey post hoc test with P In Nexus3, the immediate light curing had significantly higher bond strength (11.18±4.32) than delay methods (P=0.001). In Panavia F2.0, the 5-minute delay had significantly the highest bond strength (13.34±4.62) (P0.05).
Delay in light curing of dual-cure resin cement's had different effects on the push-out bond strength.

To report clinical outcomes after the implantation of an indigenous version of Pintucci keratoprosthesis in a patient suffering from severe ocular surface chemical burn.
Case Report: A 41 year-old man had bilateral severe acid burn 5 years before his recent presentation. He underwent penetrating keratoplasty and keratolimbal allografts OU which failed. Upon the presentation, visual acuity was light perception in both eyes. Slitlamp examination revealed severe dry eye, corneal opacities and conjunctivalization indicating total limbal stem cell deficiency OU. The left eye was considered for keratoprosthesis. The keratoprosthesis which was an indigenous version of Pintucci keratoprosthesis was manufactured in the Ophthalmic Research Center, affiliated with Shahid Beheshti University of Medical sciences, Tehran, Iran. In the first stage, ocular surface was reconstructed with oral mucus membrane graft, and keratoprosthsis was placed under the skin and orbicularis oculi muscle. Three months later, keratoprosthsis was removed and implanted in the left eye. Three months postoperatively, best corrected visual acuity was 2/10 and anatomical position was acceptable. No complications were encountered during the follow up.
The results of the first case implanted with the locally manufactured keratoprosthesis are acceptable and encourage us to implant this type of keratoprosthesis in patients with severe dry eye and total limbal stem cell deficiency.

Since sleep has an important impact on life of students and their mental health, this study designed to investigation of the relationship between quality of sleep and mental health of students in school of rehabilitation sciences, of shahid beheshti university of medical sciences. In this cross-sectional study 239 students from four field of study in rehabilitation were randomly selected. The used questionnaires were as following; demographic, mental health (GHQ-28) and pittsburgh sleep quality index(PSQI). ANOVA test was performed for data analysis. (α=0.05) 36.6% of all students had satisfactory sleep quality and the rest 63.6% had poor sleep quality. 46.2% had physical symptoms, 50.2% showed stress, 65.7% had social function disorder and 33.1% showed depression, according to mental health minor scales. There was significant relationship between sleep quality and mental health (P<0.001). There is a significant relationship between sleep quality and mental health. So, lackof sleepcan affect on students’ academic performance, daily function, physical and mental health.

Long-time erexposure to ultraviolet radiations can lead to various skin and ocular diseases. UV-blocking contact lenses due to their properties against ultraviolet radiations can protect eyes. The present study aimed to compare between ultraviolet and visible light rays transmission through soft contact lenses available in Iran. In this cross-sectional study, 6 types of contact lenses (Avaira, Biofinity, Acuvue 2, Acuvue Oasys, Ultra Wave, and Specialy S55) were purchased from reputable companies of the country, and were evaluated in terms of transmission of ultraviolet and visible light according to U.S. Food and Drug Administration of (FDA) criteria. To test the samples, a calibrated spectral transmittance-meter was used, which had the ability of evaluation of samples at wavelengths of ultraviolet type B, type A, and visible light. The data were analyzed by ANOVA and post hoc Tukey tests. The significance level was considered to be p≥0.05. In this study, none of the lenses were eligible for blocking UV radiation. Among the UV-blocking soft lenses, the Acuvue Oasys had the best performance, with a transmittance of less than 4% of UV-B and less than 45% of UV-A. All of the lenses decreased the transmittance of visible light about 4%. Considering that all of the studied contact lenses can protect eyes against UV radiation compared to other lenses, but for protection against harmful sunlight, standard sunglasses and an appropriate hat should be used together with even the best UV-blocking contact lenses.

Wearing spectacles is the most common procedure for correction of refractive error and because of its close relationship with eye; the standards of frame & lens of glasses play a very important role in preventing vision problems. The purpose of this study was to compare spherical & cylindrical power and prismatic effect of plastic ophthalmic lenses with Iranian national standards. In this Cross sectional-Comparative study 48 plastic ophthalmic single vision lenses were inspected & compared with relative national standards i.e.: ISIRI 8715-1:1385. The spherical power factor with instruments set as step 0.01, all the cases(-1.00,-3.00,-6.00) were in tolerance with limits of the standards (±0.12 D). The instrument was set for 0.01 step for cylindrical power, at -6.00 D 100% of lenses had no cylindrical power. At -3.00 & -1.00 D about 99% were in tolerance with the standards (±0.09 D).The effect of horizontal & vertical prism, at the power of -6.00 all lenses show prismatic effect but 99% were in tolerance with the standards (±0.85D). At the power of -3.00 & -1.00 D, prismatic effect of lenses were in tolerance with relative standards (±0.55, ±0.35), respectively. All single vision were collected from famous companies showed the quality of passing all factors of tests & gained Iranian national standards i.e.: ISIRI 8715-1:1385

Solar light has various electromagnetic radiations include Ultraviolet, Visible & infrared rays. Overexposure to solar ultraviolet radiations can lead to some dangerous disorders and usage of non standard sunglasses can increase foregoing harmful effects. In Iran cataract is the most common disorder produced by UV rays. This study aims to measure the transmission of ultraviolet (A and B) and visible rays according to standards through sunglasses provided from miscellaneous vendors. In this study, 150 sunglasses were assessed by spectral transmittance meter for evaluation of the transmission of visible and ultraviolet rays. In transmission of UV-A, 41.7% of brown & 42.4% of gray sunglasses could not pass defined standard criteria; in transmission of UV-B, 3.8 % of brown and 11% of gray sunglasses could not pass standard criteria. It should be noted that, buying sunglasses from miscellaneous vendors can be dangerous and is not recommended; standard sunglasses should be bought only from licensed shops.