Vision 2020 – the Right to Sight

Indications for penetrating keratoplasty in Iranian patients

BACKGROUND

The outcome of penetration into keratoplasty (PK) related to corneal disease is responsible for corneal blindness. The aim of this study is to evaluate the indications and visual outcome of PK in Imam Khomeini Hospital in Kermanshah from March 2017 to March 2019.

MATERIALS AND METHODS

Data were reviewed from the medical records of 115 PK done in the Department of Ophthalmology, Imam Khomeini Hospital, Kermanshah, from March 2017 to March 2019. Data analysis done using paired Student's t-test for hypothesis testing of grouped values of preoperative and the last follow-up best-corrected visual acuity in cases of optical and therapeutic grafts. P <0.05 was considered statistically significant.

RESULTS

In this study, the data of 115 eyes of 108 patients were reviewed. The most common indication for keratoplasty was corneal scarring including adherent leucoma, 34 (29.56%). Therapeutic keratoplasty was done for 26 patients. One case of tectonic graft was included in therapeutic keratoplasty group for analysis. There was statistically significant difference (P = 0.0001) in best-corrected visual acuity improvement from 1.36 logMAR + 0.024 (standard deviation [SD]) preoperatively to 0.357 logMAR + 0.42 (SD) postoperatively and 1.4 logMAR + 0.000 (SD) preoperatively to 0.15 logMAR + 0.55 (SD) postoperatively for optical and therapeutic grafts, respectively.

CONCLUSION

Active or treated infectious keratitis was one of the most important indications for keratoplasty. Symptoms of poor prognosis were more pronounced in this part of the country. Patients' vision after corneal transplantation was encouraging, especially in cases of optical keratoplasty.

Advances in biomedical and pharmaceutical applications of functional bacterial cellulose-based nanocomposites

Bacterial cellulose (BC) synthesized by certain species of bacteria, is a fascinating biopolymer with unique physical and mechanical properties. BC's applications range from traditional dessert, gelling, stabilizing and thickening agent in the food industry to advanced high-tech applications, such as immobilization of enzymes, bacteria and fungi, tissue engineering, heart valve prosthesis, artificial blood vessels, bone, cartilage, cornea and skin, and dental root treatment. Various BC-composites have been designed and investigated in order to enhance its biological applicability. This review focuses on the application of BC-based composites for microbial control, wound dressing, cardiovascular, ophthalmic, skeletal, and endodontics systems. Moreover, applications in controlled drug delivery, biosensors/bioanalysis, immobilization of enzymes and cells, stem cell therapy and skin tissue repair are also highlighted. This review will provide new insights for academia and industry to further assess the BC-based composites in terms of practical applications and future commercialization for biomedical and pharmaceutical purposes.

Indications and Visual Outcome of Penetrating Keratoplasty in Tertiary Eye Care Institute in Uttarakhand

INTRODUCTION

Corneal blindness forms significant proportion of visual blindness in developing countries and penetrating keratoplasty (PK) can restore vision for this. The prognosis of PK is dependent on the corneal diseases responsible for corneal blindness.

AIM

To evaluate the indications and visual outcome of PK in tertiary eye care institute in Uttarakhand.

MATERIALS AND METHODS

Data was reviewed from the medical records of 145 PK done in Department of Ophthalmology, Himalayan Institute of Medical Sciences from January 2012 to October 2014. Analysis of data was done for evaluation of the indications and visual outcome by Paired student's t-test for hypothesis testing of grouped values of preoperative and last follow-up best corrected visual acuity in cases of optical and therapeutic grafts. A p-value < 0.05 was considered statistically significant.

RESULTS

In this study data of 145 eyes of 138 patients was reviewed. The most common indication for keratoplasty was corneal scarring including adherent leucoma 48 (33.10%). Therapeutic keratoplasty was done for 33 cases with maximum 30(20.68%) cases of infectious keratitis. One case of tectonic graft was included in therapeutic keratoplasty group for analysis. There was statistically significant difference (p=.0001) in best corrected visual acuity improvement from 1.39 logMAR+ 0.022(SD) preoperatively to 0.367 logMAR+0.44(SD) postoperatively and 1.4 logMAR+.000(SD) preoperatively to 0.16 logMAR+0.57(SD) postoperatively for optical and therapeutic grafts respectively.

CONCLUSION

Infective keratitis either active or healed was the major indication for keratoplasty. Poor prognosis indications were most common in this part of the country. The visual outcome following corneal transplantation was encouraging particularly in cases of optical keratoplasty.

[Staying and working at home or considering migrating: Survey-based study of African ophthalmologists]

BACKGROUND

The shortage of ophthalmologists is a major obstacle in the struggle of fighting preventable blindness in sub-Saharan Africa. However, to date reasons affecting migration of ophthalmologists have not been completely understood.

OBJECTIVES

Evaluation of reasons reported by ophthalmologists for staying in their current work setting/country, of potential reasons for migration as well as of effects of German-African partnerships.

MATERIAL AND METHODS

In the years 2009-2011 and 2013 participants of continuous medical education courses in Ethiopia, Cameroon and Kenya were interviewed using a standardized questionnaire.

RESULTS

A total of 106 ophthalmologists participated in this survey. In the years 2009/2010 participants were mainly board certified ophthalmologists, while the 2011/2013 surveys were answered mainly by residents. The main reasons for staying in their current region/country were good working conditions, commitment to help/patriotism, possibility of further training, good income and familial ties. Professional development elsewhere and better income abroad were named as the main reasons for considering migration followed by better technical equipment elsewhere and insecurity in the home country.

CONCLUSION

Good working conditions and the possibility of further training were named as the top reasons for staying in the current region/country apart from commitment to help and familial ties. Therefore, international cooperation programs aiming at improving training of ophthalmologists and establishing an ophthalmic infrastructure may have a role in promoting ophthalmic care in Africa.

Evaluation of corneal cell growth on tissue engineering materials as artificial cornea scaffolds

The keratoprosthesis (KPro; artificial cornea) is a special refractive device to replace human cornea by using heterogeneous forming materials for the implantation into the damaged eyes in order to obtain a certain vision. The main problems of artificial cornea are the biocompatibility and stability of the tissue particularly in penetrating keratoplasty. The current studies of tissue-engineered scaffold materials through comprising composites of natural and synthetic biopolymers together have developed a new way to artificial cornea. Although a wide agreement that the long-term stability of these devices would be greatly improved by the presence of cornea cells, modification of keratoprosthesis to support cornea cells remains elusive. Most of the studies on corneal substrate materials and surface modification of composites have tried to improve the growth and biocompatibility of cornea cells which can not only reduce the stimulus of heterogeneous materials, but also more importantly continuous and stable cornea cells can prevent the destruction of collagenase. The necrosis of stroma and spontaneous extrusion of the device, allow for maintenance of a precorneal tear layer, and play the role of ensuring a good optical surface and resisting bacterial infection. As a result, improvement in corneal cells has been the main aim of several recent investigations; some effort has focused on biomaterial for its well biological properties such as promoting the growth of cornea cells. The purpose of this review is to summary the growth status of the corneal cells after the implantation of several artificial corneas.

A preliminary descriptive analysis of Corneal Transplant Registry of National Eye Bank in India

PURPOSE

To describe and analyze the Corneal Transplant Registry of National Eye Bank and also evaluate graft outcomes in India.

METHODS

All patients who underwent corneal transplant at our center within six months of setting up of Corneal Transplant Registry and installation of database at National Eye Bank were included in the study. The established database was analyzed for utilization, donor and recipient details and graft outcomes. Outcome was assessed at the end of one year follow up. The influence of various donor and recipient factors affecting outcome were evaluated. Visual outcome was analyzed in terms of shift in visual handicap category. Statistical tests like analysis of variance, Kruskal-Wallis test and Chi square tests were applied for determination of clinical significance wherever required.

RESULTS

326 corneas were received from 168 donors; of these, 234 (71.7%) were utilized for transplantation. Out of 177 patients with adequate (one year) follow up (75.6% patients), optical corneal replacement was performed in106 patients and therapeutic keratoplasty in71. 78% (82/106) patients in the optical group retained clear grafts at the end of follow up. 59.7% (49 of 82) of patients who attained clear grafts belonged to visual disability category 3 or worse pre-operatively. 59.1% of these achieved BCVA of ≥6/60 at the end of follow up; thus shifting up their visual handicap category. Primary graft failure was found to be associated with full thickness keratoplasty and not with lamellar procedures (p<0.05) and occurred in 4.2% patients (5) with optical corneal replacement whereas 7.5% patients (8) developed secondary graft failure. Age of donor (p=0.54), death enucleation time (p>0.05), cause of donor death (p=0.15), type of surgical procedures (p=0.538) and indication for surgery did not have any significant effect on outcome. 76% patients who underwent therapeutic graft achieved elimination of corneal infection.

CONCLUSIONS

The development of corneal graft registry established an effective means to evaluate our corneal transplantation services. Outcomes of sight restoring corneal transplants performed were comparable to results of graft registries from developed nations.

Validity of vision screening tests by teachers among school children in Mashhad, Iran

PURPOSE

To determine the sensitivity and specificity of vision screening in Iranian schools where teachers have provided screening services for over 10 years.

METHODS

In a cross-sectional study, using random cluster sampling, 1163 school children were selected from 14 clusters. Data of vision tests performed by teachers were derived from 847 student records and compared with data obtained by optometrists. Measurement of the uncorrected visual acuity was done using the E chart by both the teachers and the optometrists. Examinations performed by optometrists were regarded as gold standard in this study and the sensitivity and specificity of the examinations performed by teachers were evaluated against them. Uncorrected visual acuity worse than 20/25 in the better eye was considered as the cut-off point for students' visual impairment.

RESULTS

The sensitivity and specificity of the screening tests performed by the teachers were 37.5% and 92.0%, respectively. The positive and negative predictive values were 25.0% and 95.4%, respectively. There was no significant difference in the validity of the vision test between males and females (P = 0.093 for sensitivity and P = 0.052 for specificity).

CONCLUSION

Our findings showed that teachers missed a significant number of children with vision impairment and the examinations performed by teachers lacked the required sensitivity for case detection. The number of false negative results should be minimized through continued investment in accurate screening processes.

A biosynthetic alternative to human donor tissue for inducing corneal regeneration: 24-month follow-up of a phase 1 clinical study

Corneas from human donors are used to replace damaged tissue and treat corneal blindness, but there is a severe worldwide shortage of donor corneas. We conducted a phase 1 clinical study in which biosynthetic mimics of corneal extracellular matrix were implanted to replace the pathologic anterior cornea of 10 patients who had significant vision loss, with the aim of facilitating endogenous tissue regeneration without the use of human donor tissue. The biosynthetic implants remained stably integrated and avascular for 24 months after surgery, without the need for long-term use of the steroid immunosuppression that is required for traditional allotransplantation. Corneal reepithelialization occurred in all patients, although a delay in epithelial closure as a result of the overlying retaining sutures led to early, localized implant thinning and fibrosis in some patients. The tear film was restored, and stromal cells were recruited into the implant in all patients. Nerve regeneration was also observed and touch sensitivity was restored, both to an equal or to a greater degree than is seen with human donor tissue. Vision at 24 months improved from preoperative values in six patients. With further optimization, biosynthetic corneal implants could offer a safe and effective alternative to the implantation of human tissue to help address the current donor cornea shortage.

Regeneration of functional nerves within full thickness collagen-phosphorylcholine corneal substitute implants in guinea pigs

Our objective was to evaluate promotion of tissue and nerve regeneration by extracellular matrix (ECM) mimics, using corneal implantation as a model system. Porcine type I collagen and 2-methacryloyloxyethyl phosphorylcholine (MPC) were crosslinked using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) and moulded into appropriate corneal dimensions to serve as substitutes for natural corneal ECM. These were implanted as full thickness grafts by penetrating keratoplasty into the corneas of guinea pigs after removal of the host tissue, and tracked over eight months, by clinical examination, slit-lamp biomicroscopy, and esthesiometry. Histopathology and ex vivo nerve terminal impulse recordings were performed at three months and at eight months. The implants promoted regeneration of corneal cells, nerves and the tear film, while retaining optical clarity. After three months, electrophysiological recordings showed evidence of mechano-nociceptors, and polymodal units inside the implants, while cold-sensitive units were present only on the peripheral host cornea. Following eight months, the incidence of nerve activity and the frequency of spontaneous firing were higher than in control eyes as reported for regenerating fibers. Active cold nerve terminals also innervated the implant area. We show that ECM mimetic materials can promote regeneration of corneal cells and functional nerves. The simplicity in fabrication and demonstrated functionality shows potential for ECM substitutes in future clinical applications.

The value of corneal transplantation in reducing blindness

PURPOSE

To analyse the role of keratoplasty in reducing world blindness due to corneal diseases.

METHODS

Review of published literature. We collected and analysed articles published in the English language literature related to the prevalence and causes of blindness in different parts of the world, causes of corneal blindness, and outcome of corneal transplantation for various corneal diseases.

RESULTS

A total of 80% of the world's blind live in developing countries. Retinal diseases are the most important causes of blindness (40-54%) in established economy nations while cataract (44-60%) and corneal diseases (8-25%) are the most common causes of blindness in countries with less developed economies. Keratitis during childhood, trauma, and keratitis during adulthood resulting in a vascularized corneal scar and adherent leucoma are the most frequent causes of corneal blindness in developing countries. Corneal diseases are responsible for 20% of childhood blindness. Nearly 80% of all corneal blindness is avoidable. The outcome of keratoplasty for vascularized corneal scar and adherent leucoma is unsatisfactory, necessitating repeat surgery in a high proportion of these cases. Other barriers for keratoplasty in these nations are suboptimal eye banking, lack of trained human resources, and infrastructure.

CONCLUSIONS

Since the developing world carries most of the load of corneal blindness and the major causes of corneal blindness are corneal scar and active keratitis, development of corneal transplantation services need a comprehensive approach encompassing medical standards in eye banking, training of cornea specialists and eye banking personnel and exposure of ophthalmologists to care of corneal transplants for better follow-up care. However, concerted efforts should be made to develop and implement prevention strategies since most corneal blindness is preventable.