Indications for Penetrating Keratoplasty in Iran

Modified big bubble technique for deep anterior lamellar keratoplasty in keratoconus

We describe a modified technique for deep anterior lamellar keratoplasty with three modifications in big bubble pneumodissection technique; including two staged stromal trephination to avoid inadvertent full-thickness trephination, deep bevel-up needle air injection for better visualization and deeper air injection and, vicoseperation by refilling the pre-Descemet space with a viscoelastic after removing the air bubble for safe removal of the deep stromal layers. Patients with advanced keratoconus underwent deep anterior lamellar keratoplasty with pneumodissection by two-staged trephination followed by bevel-up needle deep air injection and viscoseperation. The big bubble was successfully formed in all cases and there was no case with the rupture of the Descemet's membrane (DM) during air injection or baring of DM.

Penetrating Keratoplasty: Indications and Graft Survival by Geographic Region

Corneal transplantation, or penetrating keratoplasty (PK), is the most common form of solid-organ transplantation performed worldwide. Here, we evaluated the indications for PK and rates of transplant survival around the world by geographic region. We conducted a literature search of PubMed, MEDLINE, and Google Scholar databases and identified 155 relevant studies from 41 countries published between 1987 and 2021. The most common indications for PK were keratoconus in Europe, Africa, the Middle East, Australia, New Zealand, and Central and South America, bullous keratopathy in North America, and corneal scarring in Asia. The overall global mean graft survival rates at 1-, 2-, 3-, 5-, and 10-years were 88.6%, 81.2%, 78.9%, 72.8%, and 61.2%, respectively. Through this systematic analysis of PK by region, we hope to bring a new perspective to the corneal transplantation literature and to potentially highlight global differences and unmet needs in patient care.

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.

A Review On digital image processing techniques for in-Vivo confocal images of the cornea

This work reviews the scientific literature regarding digital image processing for in vivo confocal microscopy images of the cornea. We present and discuss a selection of prominent techniques designed for semi- and automatic analysis of four areas of the cornea (epithelium, sub-basal nerve plexus, stroma and endothelium). The main context is image enhancement, detection of structures of interest, and quantification of clinical information. We have found that the preprocessing stage lacks of quantitative studies regarding the quality of the enhanced image, or its effects in subsequent steps of the image processing. Threshold values are widely used in the reviewed methods, although generally, they are selected empirically and manually. The image processing results are evaluated in many cases through comparison with gold standards not widely accepted. It is necessary to standardize values to be quantified in terms of sensitivity and specificity of methods. Most of the reviewed studies do not show an estimation of the computational cost of the image processing. We conclude that reliable, automatic, computer-assisted image analysis of the cornea is still an open issue, constituting an interesting and worthwhile area of research.

A simple empirical inventory model for managing the processed corneal tissue equitably in hospitals with demand differentiation

This paper peruses one of the most challenging healthcare concerns related to human organ transplantation. In this regard, a medical system’s health-economic objectives are investigated to (1) achieve a desirable level of health equity in offering healthcare services to patients who are differentiated in terms of medical conditions, and (2) minimize total costs incurred across managing the inventory. This paper presents the first-ever operational research study to manage processed corneal tissue (PCT). Besides, hybrid demand-oriented policies have been proposed to equitably issue and assign specific inventories to demands with distinct medical urgent levels (ULs). In this regard, a practical multi-objective mixed-integer linear programming (MOMILP) model is proposed for a system with multiple products that can be substituted with each other according to medical priorities. A goal programming (GP) approach is utilized to find the optimum solution. The applicability of the model is validated through a real case study. Finally, several sensitivity analyses are conducted to examine the effect of critical parameters on the solutions to gain useful managerial insights. The results show that the proposed health-economic trade-off is well performed and can efficiently handle the real case.

A 27-Year Report from the Central Eye Bank of Iran

Purpose

To report the 27-year statistical data from the Central Eye Bank of Iran (CEBI) and its activity.

Methods

All CEBI records regarding procured eyes, tissue utilizations, corneal transplants per capita, and indications for keratoplasty from 1991 to 2017 were analyzed.

Results

In total, 115,743 whole eyes were donated during the 27-year period. Out of the 114,169 eyes donated between 1994 and 2017, 95,314 eyes were distributed for transplantation, and 95,057 corneas were actually transplanted. The mean annual rate of corneal transplants per capita was 55.10 - 6 ± 27.10 - 6 . Although penetrating keratoplasty (PKP, 70%) was the most common technique of corneal transplantation during the study period, it exhibited a decreasing trend between 2006 and 2017 (P = 0.048). It was in contrast to Descemet stripping automated endothelial keratoplasty (DSAEK) that demonstrated an increasing trend during the same period (P < 0.001). Keratoconus (KCN, 39.70%) was the most leading indication for keratoplasty over the last three decades followed by bullous keratopathy (BK, 18.5%), corneal scar and opacities (15.7%), and graft failure (GF, 7.5%), with an increasing trend for BK, GF, and KCN. A majority of scleral tissues (83.7%) were utilized for orbital implant protection.

Conclusion

An increasing trend in the number of procured eyes was observed over the past 27 years in Iran. The most leading indications for corneal transplantation were KCN and BK. While PKP was the most common keratoplasty technique, DSAEK showed an increasing trend over the last 12 years.

Indications and Surgical Techniques for Corneal Transplantation at a Tertiary Referral Center

Purpose

The study aimed to review the indications and techniques for corneal transplantation at a tertiary referral center over a 5-year period.

Methods

Records of patients who underwent corneal transplantation at Khalili Medical Center, Shiraz, Iran from September, 2012 to September, 2017 were reviewed.

Results

A total of 1149 eyes of 956 patients underwent corneal transplantation. The most common indication was infectious corneal ulcers (n = 296, 25.8%), followed by keratoconus (n = 243, 21.1%), bullous keratopathy (n = 219, 19.1%), failed grafts (n = 117, 10.2%), non-herpetic corneal scars (n = 113, 9.8%), corneal stromal dystrophies (n = 33, 2.9%), pellucid marginal degeneration (n = 31, 2.7%), and trauma (n = 26, 2.3%); other indications included thin descemetocele, post-herpetic corneal scar, endothelial corneal dystrophies, anterior segment dysgenesis, corneal ectasia after laser in situ keratomileusis, and corneal fibrosis. Corneal transplantation techniques included penetrating keratoplasty (PKP, n = 789, 68.7%), deep anterior lamellar keratoplasty (DALK, n = 187, 16.3%), Descemet's stripping automated endothelial keratoplasty (n = 171, 14.9%), and keratolimbal allograft (n = 2, 0.1%) in descending order. In children (aged ≤18 years), the most common indication was keratoconus (n = 32, 41.6%), and the most common technique was PKP (n = 50, 64.9%). In patients aged 19-27 years, the most common indication was keratoconus (n = 89, 64.5%), and the most common technique was PKP (n = 75, 54.4%).

Conclusion

Infectious corneal ulcer was the most common indication, and PKP was the most prevalent technique in patients undergoing corneal transplantation. DALK was an emerging alternative surgical treatment in patients with corneal disorders in which corneal endothelium is spared.

A Study of Corneal Biomechanics in Delayed-Onset Mustard Gas Keratopathy Compared to Cases With Corneal Scarring and Normal Corneas

PURPOSE

This study compares the corneal biomechanical properties, as measured with Corvis ST, in three groups of cases with delayed-onset mustard gas keratopathy (DMGK), chronic corneal scarring (CCS), and those with normal corneas.

METHODS

Forty-five eyes were enrolled in the DMGK, CCS, and normal groups (15 eyes each). All patients were examined with the slitlamp and Corvis ST. Extracted corneal biomechanical parameters included first and second applanation time (AT1, AT2), first and second applanation length (AL1, AL2), first and second applanation velocity (AV1, AV2), deformation amplitude (DA), highest concavity time, peak distance, highest concavity radius (HCR), central corneal thickness, corrected intraocular pressure (IOP), and noncorrected IOP.

RESULTS

The mean age of the participants in the DMGK, CCS, and normal groups was 49.20±5.16, 60.40±22.92, and 44.60±8.32 years, respectively. Comparison between DMGK and CCS groups showed significant differences in AT1, AT2, corrected IOP, and noncorrected IOP. There were also significant differences in AT1, AT2, HCR, DA, and noncorrected IOP between the DMGK and normal groups. None of the parameters were significantly different between the CCS and normal groups.

CONCLUSION

There seems to be reduced corneal rigidity and stiffness in cases exposed to mustard gas, which causes the cornea in the DMGK group to become applanated more easily and take longer to rebound compared with the other two groups. Also, IOP was lower than normal in the DMGK group, and thus, misdiagnosis of glaucoma is likely for these patients.

An 11-Year Review of Keratoplasty in a Tertiary Referral Center in Turkey: Changing Surgical Techniques for Similar Indications

OBJECTIVES

Study aims to evaluate the indications and surgical techniques for corneal transplantation and to report changes in trends for preferred keratoplasty surgical techniques.

METHODS

Clinical records of 815 consecutive corneal transplantations between January 1, 2004 and December 31, 2014 in Haydarpasa Numune Training and Research Hospital Eye Clinic were analyzed and classified into seven broad groups according to indications. Main outcome measures were change of leading indications and trends for surgical techniques.

RESULTS

Leading indications for keratoplasty were keratoconus (KCN) (27.7%), bullous keratopathy (BK) (23%), postinfectious corneal scars (13.5%), regrafts (13.1%), corneal dystrophies (12.1%), and noninfectious corneal scars (5.4%). Regrafts were the only indication with a significantly increasing trend (P<0.01). Since the introduction of lamellar keratoplasty (LK) techniques including deep anterior lamellar keratoplasty (DALK) and Descemet stripping automated endothelial keratoplasty (DSAEK), there was a significant increasing trend in number and percentage of both LK techniques (DALK; P=0.001 and P=0.007, and DSAEK; P<0.001 and P<0.001, respectively) and a significant corresponding decline in the percentage of penetrating keratoplasty (PK) (P<0.01). Similarly, DALK and DSAEK replaced PK as the preferred surgical technique for KCN and BK indications, (P=0.007 and P=0.01, respectively). Although PK was the most common surgical technique over the 11-year period (54.7%), both anterior and posterior LK techniques showed an emerging trend as the procedures of choice when indicated.

CONCLUSIONS

No major shift was observed in the clinical indications for corneal transplantation over the previous 11 years, except for regrafts. Lamellar keratoplasty techniques largely overtook the PK technique, but PK was still the overall preferred technique in the era when both LK techniques were used.

Changing Indications in Penetrating Keratoplasty: A Systematic Review of 34 Years of Global Reporting

BACKGROUND

Penetrating keratoplasty (PK) ranks among the oldest and most common kinds of human tissue transplantation. Based on the hypothesis that reported indications for PK significantly vary between global regions and over time, the present systematic review aimed to provide a thorough overview of global PK indications as reported in peer-reviewed manuscripts.

METHODS

A literature search of PubMed and MEDLINE was conducted to retrieve articles published from January 1980 to May 2014. Indications for PK within 7 global regions were compared using a modified classification system for PK indications and analyzed via multivariate regression.

RESULTS

A total of 141 publications from 37 countries were included, recording 180 865 PK cases. Postcataract surgery edema was the predominant indication in North America (28.0%) and ranked second in Europe (20.6%), Australia (21.1%), the Middle East (13.6%), Asia (15.5%), and South America (18.6%). Keratoconus was the leading indication in Europe (24.2%), Australia (33.2%), the Middle East (32.8%), Africa (32.4%), and South America (22.8%). It ranked third in North America (14.2%). Keratitis was the primary indication in Asia (32.3%). Fuchs endothelial corneal dystrophy was the fourth most common indication in North America (12.9%) and Europe (10.2%) and fifth in South America (3.8%). Multivariate analysis supported these results and revealed individual regional changes over time.

CONCLUSIONS

Systematic analysis reveals characteristic chronological and regional differences in reported global PK indications. Leading reported indications for PK between 1980 and 2014 were keratoconus (Europe, Australia, the Middle East, Africa, and South America), pseudophakic bullous keratopathy/aphakic bullous keratopathy (North America), and keratitis (Asia).

Trends in Indications and Techniques of Corneal Transplantation in Iran from 2006 to 2013; an 8-year Review

Purpose:

To report changing trends in indications and techniques of corneal transplantation in Iran.

Methods:

We reviewed eye bank records of 47,129 patients who had undergone corneal transplantation between 2006 and 2013 at different eye centers throughout Iran.

Results:

The most common indication for corneal transplantation was keratoconus (KCN, n = 21,350 eyes, 45.3%), followed by bullous keratopathy (BK, n = 8,566 eyes, 18.2%), corneal opacity and scar (COS, n = 7,158 eyes, 15.2%), graft failure (n = 3,252 eyes, 6.9%), corneal dystrophies (n = 2,553 eyes, 5.4%), and infectious keratitis (n = 2,238 eyes, 4.7%). Over the study period, there was a significant increase in the frequency of BK (P = 0.001) and graft failure (P = 0.025), and a significant decrease in the relative frequency of COS (P = 0.012). The prevalence of KCN (P = 0.172), infectious keratitis (P = 0.107), and corneal dystrophies (P = 0.836) remained unchanged. The most common technique of corneal transplantation was penetrating keratoplasty (PKP, n = 33,476 eyes, 71.0%), followed by deep anterior lamellar keratoplasty (DALK, n = 8,363 eyes, 17.7%), Descemet's stripping automated endothelial keratoplasty (DSAEK, n = 3,516 eyes, 7.5%), tectonic (n = 1752, 3.7%), and keratolimbal allograft (KLAL, n = 19 eyes, 0.1%). Regarding the shift in surgical techniques, a significant increase was observed in DSAEK (P < 0.001), whereas PKP was significantly decreased (P = 0.005) over the 8-year period. No significant change was seen in the rates of DALK (P = 0.354), tectonic graft (P > 0.999) and KLAL (P = 0.151).

Conclusion:

KCN was the most common indication and PKP was the most prevalent technique used for corneal transplantation. Significant changes in surgical techniques were observed over the past 8 years; DSAEK demonstrated an increasing trend while PKP showed a decrease.

Changing indications and techniques for corneal transplantations at a tertiary referral center in Turkey, from 1995 to 2014

Background

Indications for corneal transplantation in developed and developing nations differ according to the different spectrum of corneal disease in each country.

Objective

The purpose of this study is to analyze the changing indications and surgical techniques for corneal transplantation over the past 20 years at a tertiary referral center in Turkey.

Methods

We retrospectively reviewed the records of patients who underwent keratoplasty from January 1995 to December 2014 (between 1995 and 2004, period 1, and between 2005 and 2014, period 2). Patients’ demographic data, indications for corneal transplantation, and the type of surgery were recorded.

Results

The number of keratoplasties performed ranged from 548 in period 1 to 782 in period 2. Between 1995 and 2004, the leading indications were keratoconus (34.1%), bullous keratopathy (17%), and non-herpetic corneal scar (13.3%), and between 2005 and 2014, they were keratoconus (33.8%), corneal stromal dystrophy (14.2%), and bullous keratopathy (12.7%). All the keratoplasties performed in the 1995–2004 period were penetrating keratoplasty (PKP). During the period 2005–2014, PKP accounted for 93%, automated lamellar keratoplasty 5.8%, and deep anterior lamellar keratoplasty 1.2% of all corneal transplantations.

Conclusion

Keratoconus was the leading indication for keratoplasty in both periods. In the 2005–2014 period, corneal stromal dystrophy increased significantly. All the keratoplasties performed in period 1 and 93% of all keratoplasties performed in period 2 were PKP.

Indications for and techniques of keratoplasty at Vietnam National Institute of Ophthalmology

AIM

To report the indications for and techniques of corneal transplantation at Vietnam National Institute of Ophthalmology (VNIO) over a period of 12y (2002-2013).

METHODS

Records of patients who had undergone corneal transplantation at VNIO from January 1, 2002 to January 1, 2014 were reviewed to determine the indication for and type of corneal transplant performed. Patient age, gender, indication for corneal transplantation and surgical technique were recorded and analyzed.

RESULTS

Corneal transplantation were underwent in 1390 eyes of 1278 patients with a mean age of 44.9±18.1y during the period under review. The most common indication was infectious corneal ulcer (n=670; 48.2%), followed by corneal scar (n=333, 24.0%), corneal dystrophy (n=138, 9.9%) and failed graft (n=112, 8.1%). Nearly all procedures performed were penetrating keratoplasty (n=1300, 93.5%), with a few lamellar keratoplasty procedures performed: lamellar keratoplasty (n=52, 3.7%), Descemet's stripping automated endothelial keratoplasty (n=27, 1.9%) and deep anterior lamellar keratoplasty (n=11, 0.8%).

CONCLUSION

While the most common indication for keratoplasty was infectious keratitis, nearly all indications for corneal transplantation were managed with penetrating keratoplasty. However, lamellar keratoplasty techniques, including deep anterior lamellar keratoplasty and Descemet's stripping automated endothelial keratoplasty, are being performed with increasing frequency for isolated stromal and endothelial disorders, respectively.

Corneal Collagen Cross-Linking in the Treatment of Progressive Keratoconus: A Randomized Controlled Contralateral Eye Study

BACKGROUND

To assess the short-term efficacy and safety of corneal collagen cross-linking (CXL) in preventing the progression of keratoconus (KCN).

MATERIALS AND METHODS

This randomized controlled clinical trial enrolled 26 patients diagnosed with bilateral progressive KCN and were eligible for CXL. In each patient, one eye was randomly selected for treatment, and the contralateral eye served as the control. The patients underwent CXL with riboflavin drops and ultraviolet radiation in the treated eye. One year follow-up data are presented. Postoperatively, patients were assessed for progression of KCN, visual changes, and other findings. The main outcome measures were maximum simulated keratometry (K-max), best spectacle-corrected visual acuity (BSCVA), and average simulated keratometry. P <0.05 was considered as statistically significant.

RESULTS

In the treated eyes, the mean K-max values decreased by 0.22 D at 1-year postoperatively and increased by 0.41 D in the control group. This difference was statistically significant (P < 0.001). BSCVA improved slightly (a decrease of 0.13 LogMAR) and decreased slightly in the control group (a 0.01 LogMAR increase). The difference between groups was statistically significant (P = 0.014). There was no decrease in visual acuity attributable to complications of CXL in the treated eyes. At 1-year, the keratometry in 3 (12%) treated eyes increased by more than 0.50 D and were considered cases of failed treatment.

CONCLUSION

Preliminary and 1-year results indicate CXL can halt the progression of KCN in most cases without causing serious complications.

Modified deep anterior lamellar keratoplasty for the treatment of advanced keratoconus with steep corneal curvature to help in eliminating the wrinkles in the Descemet's membrane

Aims:

To determine the clinical efficacy of modified deep anterior lamellar keratoplasty (DALK) for the treatment of advanced-stage keratoconus with steep curvature.

Materials and Methods:

In this interventional, non-comparative case series, 30 patients with advanced stages of keratoconus and curvature of more than 60 D underwent a modified DALK procedure. In this technique, after big-bubble formation, posterior stromal lamella was cut and removed 5 mm centrally (baring Descemet's membrane completely) with posterior stromal layer remaining peripherally.

Results:

The study included 30 eyes (30 patients with a mean ± SD age of 25 ± 5.4 years). The follow-up examination was performed for all participants up to 12 months after the surgery. The mean uncorrected visual acuity (UCVA) increased from 20/800 before the surgery to a subsequent 3/10 (P =0.12). Likewise, best spectacle corrected visual acuity (BSCVA) improved, reaching 6/10 postoperatively (former quantity 20/200) (P =0.18). In addition, mean keratometry and keratometric astigmatism managed to achieve considerable improvement, from 58.8 ± 5.4 D to 46.5 ± 2.1 D and 7.8 ± 2.1 to 4.54 ± 1.54 D, respectively (P =0.52). Descemet's membrane wrinkling was not seen in any patient postoperatively.

Conclusions:

This technique is effective in restoring acceptable vision and corneal regularity in advanced cases of keratoconus with a curvature more than 60 D who are also at risk of Descemet's membrane wrinkling after DALK. Therefore, this procedure could prevent from Descemet membrane wrinkling in such cases.

Indications and techniques employed for keratoplasty in the Eastern province of Saudi Arabia: 6 years of experience

BACKGROUND AND OBJECTIVES

Keratoplasty services in Saudi Arabia have progressed steadily in the past few decades. We sought to identify the leading indications and types of keratoplasty performed in the Eastern Province of Saudi Arabia over a six-year period and to compare these indications with published data.

DESIGN AND SETTING

This was a retrospective descriptive analysis of the records of patients who underwent keratoplasty at four ophthalmology centers in the Eastern Province between 2008 and 2013.

PATIENTS AND METHODS

All keratoplasty procedures were included in the analysis. The primary surgical indication and type of surgery were identified for each case.

RESULTS

Keratoplasties included 570 penetrating keratoplasty, 217 deep lamellar keratoplasty, 80 triple procedures, 24 descemet stripping automated endothelial keratoplasty and 12 Boston keratoprosthesis implantations. The mean age of all patients was 28.8 years (range 14-72 years), and 58.9% of the patient were males. The lead.ing indication for keratoplasty was keratoconus 53.10%, bullous keratopathy 13.80%, corneal scarring 10.7%, regrafts 9.1%, and stromal dystrophies 4.9%.

CONCLUSIONS

In this study, the leading indications for keratoplasty were keratoconus, bullous keratopathy, corneal scarring, regrafts and stromal dystrophies. A significant increasing trend for descemet's stripping automated endothelial keratoplasty surgeries was observed in spite of the number of cases.

Effect of donor graft quality on clinical outcomes after deep anterior lamellar keratoplasty

PURPOSE

The aim of this study was to determine the effect of donor features, including age, death-to-preservation time, preservation-to-surgery time, graft rating, and endothelial cell features, on visual and refractive outcomes and complications occurring after deep anterior lamellar keratoplasty (DALK) in patients with keratoconus.

METHODS

In this retrospective study, 290 consecutive keratoconic eyes underwent DALK using donor corneas of different qualities, ranging from fair to excellent. Donor corneas were stored in intermediate-term storage medium. Donor data included age and sex, death-to-preservation time, preservation-to-surgery time, epithelial and stromal status, endothelial cell density and morphology, and graft rating. Postoperative outcomes included visual acuity, refractive error, epithelial problems, suture-related complications, graft rejection, and graft transparency. A multivariate regression analysis was used to assess the correlation between donor characteristics and postoperative outcomes.

RESULTS

Mean donor and recipient ages were 33.4 ± 13.1 and 27.7 ± 8.0 years, respectively. The mean follow-up period was 38.2 ± 20.2 months. The presence of epithelial defects on postoperative day 1 had a significant correlation with donor epithelial sloughing (R = 0.26, P < 0.001), preservation-to-surgery time (R = 0.21, P = 0.001), and graft rating (R = -0.17, P = 0.004). Graft stromal edema on postoperative day 1 was significantly correlated with donor epithelial sloughing (R = 0.31, P < 0.001), preservation-to-surgery time (R = 0.24, P < 0.001), and graft rating (R = -0.28, P < 0.001). Suture-related complications, graft rejection episodes, graft clarity, visual acuity, and refractive outcomes at the final follow-up examination were found to have no correlations with any donor factors.

CONCLUSIONS

The use of low-quality donors for DALK increased the rate of epithelial defects and stromal edema immediately postoperatively. However, the donor features had no influence on visual and refractive outcomes and complications.

Keratoconus: tissue engineering and biomaterials

Keratoconus (KC) is a bilateral, asymmetric, corneal disorder that is characterized by progressive thinning, steepening, and potential scarring. The prevalence of KC is stated to be 1 in 2000 persons worldwide; however, numbers vary depending on size of the study and regions. KC appears more often in South Asian, Eastern Mediterranean, and North African populations. The cause remains unknown, although a variety of factors have been considered. Genetics, cellular, and mechanical changes have all been reported; however, most of these studies have proven inconclusive. Clearly, the major problem here, like with any other ocular disease, is quality of life and the threat of vision loss. While most KC cases progress until the third or fourth decade, it varies between individuals. Patients may experience periods of several months with significant changes followed by months or years of no change, followed by another period of rapid changes. Despite the major advancements, it is still uncertain how to treat KC at early stages and prevent vision impairment. There are currently limited tissue engineering techniques and/or "smart" biomaterials that can help arrest the progression of KC. This review will focus on current treatments and how biomaterials may hold promise for the future.

Corneal blindness and xenotransplantation

Approximately 39 million people are blind worldwide, with an estimated 285 million visually impaired. The developing world shoulders 90% of the world's blindness, with 80% of causative diseases being preventable or treatable. Blindness has a major detrimental impact on the patient, community, and healthcare spending. Corneal diseases are significant causes of blindness, affecting at least 4 million people worldwide. The prevalence of corneal disease varies between parts of the world. Trachoma, for instance, is the second leading cause of blindness in Africa, after cataracts, but is rarely found today in developed nations. When preventive strategies have failed, corneal transplantation is the most effective treatment for advanced corneal disease. The major surgical techniques for corneal transplantation include penetrating keratoplasty (PK), anterior lamellar keratoplasty, and endothelial keratoplasty (EK). Indications for corneal transplantation vary between countries, with Fuchs' dystrophy being the leading indication in the USA and keratoconus in Australia. With the exception of the USA, where EK will soon overtake PK as the most common surgical procedure, PK is the overwhelming procedure of choice. Success using corneal grafts in developing nations, such as Nepal, demonstrates the feasibility of corneal transplantation on a global scale. The number of suitable corneas from deceased human donors that becomes available will never be sufficient, and so research into various alternatives, for example stem cells, amniotic membrane transplantation, synthetic and biosynthetic corneas, and xenotransplantation, is progressing. While each of these has potential, we suggest that xenotransplantation holds the greatest potential for a corneal replacement. With the increasing availability of genetically engineered pigs, pig corneas may alleviate the global shortage of corneas in the near future.

Penetrating keratoplasty for keratoconus: visual and graft survival outcomes

OBJECTIVES

To evaluate the complications, and visual and graft survival outcomes in eyes that had undergone penetrating keratoplasty (PKP) for keratoconus.

METHODOLOGY

This restrospective study includes 311 patients with keratoconus who had undergone PKP between January 1, 2001, and December 31, 2002, at King Khaled Eye Specialist Hospital. All patients were followed up postoperatively (maximum follow-up, 65.77 months).

RESULTS

The mean age of patients with keratoconus at transplantation was 23.72 years. A preoperative best spectacle-corrected visual acuity (BSCVA) OF 20/40 or better was achieved in 13 eyes (4.2%). At a mean follow-up of 27 months, 212 eyes (68.2%) achieved a BSCVA of 20/40 or better. Postoperative visual acuity was significantly associated with preoperative visual acuity (P < 0.00). Only 6 eyes (1.9%) experienced graft failure, with a mean follow-up of 23.62 months. The graft rejection rate (6.8%) was a significant risk factor for failure (P = 0.00). Age, gender, corneal graft diameter, and intraoperative vitreous loss had no statistically significant effects on the PKP outcome (P> 0.05). Kaplan-Meier analysis revealed that the probabilities of graft survival were 99.8% at 1 year and 97.6% at 5 years after transplantation.

CONCLUSION

Performing PKP in eyes with keratoconus is associated with good visual results and an excellent graft outcome.

Endothelial cell whole genome expression analysis in a mouse model of early-onset Fuchs' endothelial corneal dystrophy

PURPOSE

To investigate the endothelial gene expression profile in a Col8a2 Q455K mutant knock-in mouse model of early-onset Fuchs' endothelial corneal dystrophy (FECD) and identify potential targets that can be correlated to human late-onset FECD.

METHODS

Diseased or normal endothelial phenotypes were verified in 12-month-old homozygous Col8a2(Q455K/Q455K) mutant and wild-type mice by clinical confocal microscopy. An endothelial whole genome expression profile was generated by microarray-based analysis. Result validation was performed by real-time PCR. Endothelial COX2 and JUN expression was further studied in human late-onset FECD compared to normal samples.

RESULTS

Microarray analysis demonstrated endothelial expression of 24,538 genes (162 up-regulated and 172 down-regulated targets) and identified affected gene ontology terms including Response to Stress, Protein Metabolic Process, Protein Folding, Regulation of Apoptosis, and Transporter Activity. Real-time PCR assessment confirmed increased Cox2 (P = 0.001) and Jun mRNA (P = 0.03) levels in Col8a2(Q455K/Q455K) mutant compared to wild-type mice. In human FECD samples, real-time PCR demonstrated a statistically significant increase in COX2 mRNA (P < 0.0001) and JUN mRNA (P = 0.002) and tissue microarray analysis showed increased endothelial COX2 (P = 0.02) and JUN protein (P = 0.04).

CONCLUSIONS

The present study provides the first endothelial whole genome expression analysis in an animal model of FECD and represents a useful resource for future studies of the disease. In particular endothelial COX2 up-regulation warrants further investigation of its role in FECD.

Changing indications and surgical techniques for corneal transplantation between 2004 and 2009 at a tertiary referral center

Purpose:

The aim of this study is to report the indications, techniques, and clinical outcomes of corneal transplantation and investigate any changing trends in surgical techniques over a 6 year period.

Materials and Methods:

Records of patients who had undergone any kind of corneal transplantation at Labbafinejad Medical Center, Tehran, Iran, from January 2004 to December 2009 were reviewed to determine the indications and types of corneal transplantation. Postoperative best-corrected visual acuity, refractive error, graft clarity, and complications were reported.

Results:

During this period, 1859 eyes of 1624 patients with a mean age of 41.3 ± 21.3 years underwent corneal transplantation. The most common indication was keratoconus (38.4%) followed by aphakic/pseudophakic bullous keratopathy (11.7%), previous failed grafts (10.6%), infectious corneal ulcers (10.1%), non-herpetic corneal scars (7.6%), trachoma keratopathy (4.7%), stromal corneal dystrophies (4.6%), post-herpetic corneal scar (3.7%), Fuchs’ endothelial dystrophy (0.8%), and congenital hereditary endothelial dystrophy (0.4%). Techniques of corneal transplantation included penetrating keratoplasty (PKP; 70.9%), deep anterior lamellar keratoplasty (DALK; 20.1%), conventional lamellar keratoplasty (LKP; 4.4%), and Descemet's stripping automated endothelial keratoplasty (DSAEK; 2.3%). Over the study period, there was a significant increase in the relative frequency of infectious corneal ulcers, failed grafts, and trachoma keratopathy. Additionally, a significant reduction was observed in PKP and LKP procedures, and volume of DALK and DSAEK increased significantly. At final follow-up, 69.0% of grafts were clear in the PKP group. This figure was 82.6%, 82.7%, and 97.6% in the DALK, LKP, and DSAEK groups, respectively.

Conclusion:

Keratoconus was the most common indication and PKP was the most prevalent technique used for corneal transplantation. However, significant changes in the indications and surgical techniques were observed from 2004 to 2009.

Prospective longitudinal study of corneal collagen cross-linking in progressive keratoconus

BACKGROUND

Collagen cross-linking has been reported to be effective in treating progressive keratoconus, and this study aims to evaluate the long-term efficacy of this procedure.

DESIGN

Prospective longitudinal interventional study of patients with progressive keratoconus who underwent cross-linking in a tertiary referral hospital.

PARTICIPANTS

Thirty-five patients (51 eyes) who underwent cross-linking with a mean follow-up of 14.38 ± 9.36 months (range 6-48) were compared with a control group of 25 fellow eyes that did not undergo the procedure.

METHODS

Cross-linking was performed using 0.1% riboflavin (in 20% dextran T500) and ultraviolet A irradiation (370 nm, 3 mW/cm(2) , 30 min).

MAIN OUTCOME MEASURES

Maximum keratometry in dioptres, logMAR best spectacle-corrected visual acuity, cylindrical power, manifest refraction spherical equivalent and central corneal thickness.

RESULTS

Analysis of the treated group demonstrated a significant flattening of maximum keratometry by 0.96 ± 2.33 dioptres (P = 0.005) and a significant improvement in visual acuity by 0.05 ± 0.13 logMAR (P = 0.04). In the control group, maximum keratometry increased significantly by 0.43 ± 0.85 dioptres (P = 0.05), and visual acuity decreased by mean 0.05 ± 0.14 (P = 0.2). No statistical differences were noted regarding cylindrical power, spherical equivalent or corneal thickness in both groups.

CONCLUSIONS

Results indicate that corneal collagen cross-linking using riboflavin and ultraviolet A is effective as a therapeutic option in cases of progressive keratoconus by reducing the corneal curvature and by improving the visual acuity in these patients.

Trends in the indications for penetrating keratoplasty in Shandong, 2005-2010

AIM

To identify the current indications and the trend shifts for penetrating keratoplasty (PKP) in Shandong.

METHODS

The medical charts of all patients who underwent PKP at Shandong Eye Institute from June 1, 2005 to May 31, 2010 were analysed retrospectively.

RESULTS

A total of 875 patients (875 eyes) received PKP in this 5-year period, accounting for 61.6% of all corneal transplantation surgeries. The leading indications for PKP were infectious keratitis (37.1%), HSK (19.1%), keratoconus (11.2%), bullous keratopathy (8.5%), regrafting (6.7%) and corneal scarring (4.8%). The percentage of PKP for keratoconus declined year by year, whereas the percentage of bullous keratopathy had a mild annual increase. Fungal infections accounted for 65.2% of the infectious keratitis cases, remaining the leading cause of corneal infection. In addition, 54.1% of bullous keratopathy cases were associated with cataract surgery. The leading initial diagnoses associated with regrafting were infectious keratitis (38.9%), HSK (18.6%) and corneal burn (16.9%). The major causes of regrafting included graft endothelial dysfunction (39.0%), graft ulcer (28.8%) and primary disease recurrence (15.3%).

CONCLUSION

Infectious keratitis remained the leading indication for PKP in Shandong, and fungal infections were still the major cause of corneal infections. There was an increasing trend in the percentage of PKP cases indicated for bullous keratopathy but a decline in the same for keratoconus. Even with a decline in the overall proportion among all corneal transplantation surgeries, PKP is still the major corneal transplant choice in Shandong.

Deep anterior lamellar keratoplasty: indications, surgical techniques and complications

The concept of lamellar keratoplasty (LK) is not new. However, it had been abandoned and largely replaced by the time-honored technique of penetrating keratoplasty (PK) because LK is technically demanding, time consuming and gives suboptimal visual outcomes due to interface irregularity arising from manual lamellar dissection. Recent improvements in surgical instruments and introduction of new techniques of maximum depth of corneal dissection as well as inherent advantages such as preservation of globe integrity and elimination of endothelial graft rejection have resulted in a re-introduction of LK as an acceptable alternative to conventional PK. This review article describes the indications, different techniques, clinical outcomes and complications of deep anterior LK.

Deep anterior lamellar keratoplasty versus penetrating keratoplasty for keratoconus: a clinical trial

PURPOSE

To compare deep anterior lamellar keratoplasty (DALK) using the big-bubble technique to penetrating keratoplasty (PK) in patients with keratoconus.

MATERIALS AND METHODS

In this clinical trial, patients with moderate to advanced keratoconus with poor spectacle-corrected visual acuity and intolerant to contact lens wear were enrolled. DALK was performed using the big-bubble technique, and a full-thickness donor cornea without Descemet membrane was sutured to the recipient bed. PK was performed conventionally with a Hessburg-Barron suction trephine. Three types of suturing were used for both groups. Postoperative refractive errors, best-corrected visual acuity (BCVA), contrast sensitivity function (CSF), and higher order aberrations (HOAs) were compared between the study groups.

RESULTS

The study included 81 eyes of 81 patients. Forty-six eyes underwent DALK from which 4 were excluded because of failure to achieve bared Descemet membrane. Thirty-five eyes received PK. Mean patient age was 26.91 ± 7.9 versus 30.89 ± 10.3 years in the DALK and PK groups, respectively (P = 0.06). Mean follow-up period was 22.0 ± 7.9 months in the DALK group and 24.6 ± 3.5 months in the PK group (P = 0.32). Mean postoperative spherical equivalent refractive error was -3.23 ± 3.4 diopters in the DALK group versus -2.22 ± 4.6 diopters in the PK group (P = 0.28), and mean postoperative BCVA was 0.18 ± 0.08 and 0.15 ± 0.10 logarithm of the minimum angle of resolution, respectively (P = 0.12). CSF and total aberrations and HOAs were comparable in the study groups.

CONCLUSIONS

DALK is an effective alternative surgical procedure for patients with keratoconus; the outcomes are comparable to PK in terms of refractive errors, BCVA, CSF, and HOAs.

Deep anterior lamellar keratoplasty in patients with keratoconus: big-bubble technique

PURPOSE

To evaluate the visual and refractive outcomes after deep anterior lamellar keratoplasty (DALK) using the big-bubble technique in eyes with keratoconus.

METHODS

In this case series, eyes with moderate to advanced keratoconus underwent DALK. All of them had unacceptable spectacle-corrected visual acuity or were contact lens intolerant. DALK was performed using the big-bubble technique. Full thickness donor cornea without Descemet's membrane (DM) was sutured to the recipient bed with three different suturing techniques. The visual acuity (presented in logMAR), refractive status, intraoperative and postoperative complications were evaluated.

RESULTS

A total of 129 consecutive eyes of 121 patients were included. In 3 eyes, the operation was converted to penetrating keratoplasty. Therefore, 126 eyes (79 male) were enrolled in the study. Mean patient age at the time of surgery was 26.08 +/- 7.6 years. Mean follow-up period was 21.62 +/- 9.0 months. Mean preoperative corrected visual acuity was 1.27 +/- 0.4 logMAR, increasing to 0.25 +/- 0.2 logMAR at final follow-up examination (P < 0.001). Postoperative mean spherical equivalent refractive error, refractive and keratometric astigmatism were -3.41 +/- 3.1 D, 3.04 +/- 2.3 D, and 3.67 +/- 2.1 D, respectively. Bared DM was achieved in 103 eyes, whereas in 23 eyes pre-Descemet dissection was performed. DM perforation occurred in 5 eyes. The main complications encountered were filamentary keratitis, subepithelial graft rejection, and astigmatism.

CONCLUSIONS

: DALK using the big-bubble technique appears to be a safe and effective procedure for eyes with moderate to advanced keratoconus. In case of extensive intraoperative DM perforation, it does not pose any limitation to ongoing penetrating keratoplasty.