|Year : 2014 | Volume
| Issue : 2 | Page : 234-238
Assessment and evaluation of visual acuity, indications, and complications after penetrating keratoplasty
Moustafa K Nassar1, Abd El-Rahman E Sarhan1, Moatz F El-Sawey1, Ahmed I Alsherbiny2
1 Department of Ophthalmology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
2 Cornea Unit, National Eye Center Hospital, Cairo, Egypt
|Date of Submission||26-Mar-2013|
|Date of Acceptance||10-Jun-2013|
|Date of Web Publication||26-Sep-2014|
Ahmed I Alsherbiny
MBBCh, 8 Street No. 4, El-Madina El-Togaria, Kafr El-Sheikh City, Kafr El-Sheikh Governate
Source of Support: None, Conflict of Interest: None
The aim of the study was to assess and evaluate the indications of penetrating keratoplasty (PKP), visual outcome, complications, and causes of suboptimal visual acuity after PKP.
PKP involves surgical removal of diseased or damaged cornea from the host and replacement with a full-thickness donor cornea.
Patients and methods
PKP alone or triple procedure (PKP combined with extracapsular cataract extraction and intraocular lens implantation) was performed in 50 eyes of 50 patients at National Eye Center Hospital, Cairo, Egypt, between 1 January 2009 and 31 December 2011. The outcome was evaluated in terms of graft survival (number of clear grafts at final follow-up) and final best-corrected visual acuity.
Of 50 patients who underwent PKP, 66% were male patients and 34% were female patients. The mean recipient age was 36.5 years (range 9-78 years). Leading indication of PKP was keratoconus (36%). PKP alone was performed in 88% patients, and 12% patients underwent triple procedure. Follow-up period after surgery was on the first postoperative day and after 1 week, 1 month, and 3 months. Overall graft survival was 86%. Excluding failed grafts, final best-corrected visual acuity achieved was 0.5 or better in 4% patients, 0.3-0.16 in 54% patients, 0.1-0.016 in 28% patients, and less than counting fingers (CF) in 14% patients. Keratoconus had most favorable outcome with graft survival of 94.4% and final visual acuity of 0.16 or better in 83.3% patients. Graft survival and final best-corrected visual acuity of 0.16 or better were found in remaining indications: corneal scar due to trauma (90 and 40%), corneal scar due to infection (66.7 and 44.4%), corneal dystrophy (100 and 71.4%), and other indications (66.7 and 16.7%).
This series showed that PKP is an effective procedure for corneal disease with poor vision. Visual outcome was good especially in cases of keratoconus.
Keywords: Cornea, graft, keratoconus, penetrating keratoplasty, visual acuity
|How to cite this article:|
Nassar MK, Sarhan ARE, El-Sawey MF, Alsherbiny AI. Assessment and evaluation of visual acuity, indications, and complications after penetrating keratoplasty. Menoufia Med J 2014;27:234-8
|How to cite this URL:|
Nassar MK, Sarhan ARE, El-Sawey MF, Alsherbiny AI. Assessment and evaluation of visual acuity, indications, and complications after penetrating keratoplasty. Menoufia Med J [serial online] 2014 [cited 2020 Sep 21];27:234-8. Available from: http://www.mmj.eg.net/text.asp?2014/27/2/234/141661
| Introduction|| |
The importance of corneal disease as a major cause of blindness in the world today remains second only to cataract, but its epidemiology is complicated and encompasses a wide variety of infectious and inflammatory eye diseases. In addition, the prevalence of corneal blindness varies from country to country and even from one population to another, depending on many factors, such as availability and general standards of eye care .
Penetrating keratoplasty (PKP) involves surgical removal of diseased or damaged cornea from the host and replacement with a full-thickness donor cornea. The major goals of PKP are to improve visual acuity, to maintain the integrity of the eye, and to treat various infections .
The role of corneal transplantation has grown steadily and the procedure is practised more widely than all other forms of clinical allotransplantation. Corneal transplantation has the potential to reverse visual loss in millions of people. Unfortunately, the potential of the procedure is limited by shortage of corneas, particularly in places where corneal disease is common, such as in many rural communities in developing countries .
We performed a retrospective study to evaluate the visual outcomes after PKP. The surgeon was the same in all procedures. The purpose of this study was to evaluate the outcome of PKP at National Eye Center in Egypt.
Our aim of this work was to assess and evaluate the indications of PKP, visual outcome, complications, and causes of suboptimal visual acuity after PKP, which is defined as visual acuity less than 0.16.
| Patients and methods|| |
We reviewed the hospital charts of PKP performed at National Eye Center Hospital, Cairo, Egypt, between 1 January 2009 and 31 December 2011. Information that was reviewed included patients sex, age, date of surgery, preoperative clinical diagnosis, preoperative and postoperative visual acuity, graft clarity, complications, and causes of postoperative decreased vision. The type of procedure was defined as PKP alone and triple procedure (PKP combined with an extracapsular cataract extraction and intraocular lens implantation). Each graft included in this study had follow-up on the first postoperative day and after 1 week, 1 month, and 3 months. Best-corrected visual acuity data were categorized by decimal notation: 1.0-0.5, 0.3-0.16, 0.1-0.016, and less than count fingers. Graft clarity was defined as either clear or opaque. Any graft that was not clear in the central visual axis was classified as opaque irrelative to presence of rejection or not. Graft survival was defined as number of clear grafts at final follow-up and graft failure as number of grafts with irreversible loss of optical clarity.
| Results|| |
Between 1 January 2009 and 31 December 2011, 50 patients underwent PKP at Egyptian National Eye Center Hospital. Of the 50 PKPs, there were more male patients, 33 (66%), as compared with female patients, 17 (34%). The mean age of patients was 36.5 years (range 9-78 years), with a SD of 17.6 years. Surgical procedure was performed more on the left eye, 27 (54%), as compared with the right eye, 23 (46%).
Keratoconus was the most common indication of PKP and accounted for 18 (36%) cases. Corneal scar due to trauma was the second most common indication and accounted for 10 (20%) cases. Corneal scar due to infection ranked as the third most common indication and accounted for nine (18%) cases. Corneal dystrophy was the fourth leading overall indication for PKP in this study and accounted for seven (14%) cases. Bullous keratopathy was the fifth most frequent indication for PKP and accounted for three (6%) cases. Then corneal abscess was the sixth indication and accounted for two (4%) cases. The least common indication in this report was regraft and accounted for one (2%) case.
Preoperative best-corrected visual acuity in all patients was 0.1 or worse. PKP alone was performed in 44 (88%) patients, and six (12%) patients underwent triple procedure.
Seven grafts were opaque during follow-up. Three grafts showed corneal graft failure after operation. Two grafts showed corneal graft rejection [Figure 1] and two grafts were opaque due to endophthalmitis [Figure 2].
The patients with clear graft who had less than 0.16 visual acuity had diabetic retinopathy (four eyes), glaucoma (one eye), cataract (one eye), and undiagnosed yet (one eye).
Overall graft survival was 86.0% at the last follow-up. The probability of survival at last follow-up among the keratoconus grafts was 94.4% and in the nonkeratoconus grafts was 84.3% [Table 1].
Last follow-up best-corrected visual acuity (after eliminating failed grafts) of 0.5 or better was achieved in two (4.7%) patients, 0.3-0.16 in 27 (62.8%) patients, 0.1-0.016 in 14 (32.5%) patients, and no patient was recorded for less than CF [Table 2].
In keratoconus, 15 (83.3%) patients achieved final best-corrected visual acuity of 0.16 or better, followed by patients with corneal dystrophy five (71.4%). In patients with corneal scar due to infection, four (44.4%) patients achieved 0.16 or better vision and in patients with corneal scar due to trauma, four (40%) patients achieved final best-corrected visual acuity of 0.16 or better.
Complications encountered in patients were persistent epithelial defect in five (10%) [Figure 3], graft failure in three (6%), graft rejection in two (4%) [Figure 1], endophthalmitis in two (4%) [Figure 2], and recurrence of postherpetic corneal opacity in one (2%).
| Discussion|| |
PKP is an effective treatment for corneal diseases with poor vision. The outcome of PKP depends upon indications, operative techniques, and postoperative care.
This study presents the results of 50 eyes of 50 patients who received corneal grafts at National Eye Center Hospital during 3-year period from January 2009 to December 2011.
The present study showed that keratoconus was the major indication for PKP and accounted for 36% of all the transplants performed. Corneal scar due to trauma was the second most common indication (20%), followed by corneal scar due to infection (18%), corneal dystrophy (14%), bullous keratopathy (6%), corneal abscess (4%), and regraft (2%).
Keratoconus was the first indication for PKP as Claesson et al.  reported (29%), followed by bullous keratopathy (21%). Rahman et al.  reported that keratoconus is the main indication (24%) followed by bullous keratopathy (21%). Sugar and Sugar  reviewed a number of large series of graft by decade and combined the results. It was evident that corneal edema after cataract surgery was the main cause for corneal dysfunction requiring PKP. Bhatti et al.  reported that corneal scar is the major indication (64.7%) followed by keratoconus (30%). Muraine et al.  reported that the main cause is bullous keratopathy (28%) followed by keratoconus (20%). In Al-Yousuf et al.'s  study, regraft was the first cause (40.9%) followed by keratoconus (15%).
The most common procedure associated with PKP was extracapsular lens extraction with intraocular lens implantation (triple procedure). PKP alone was performed in 88% patients, and 12% patients underwent triple procedure in our series. In a study by Chaidaroon and Lewsakul  62.2% of patients underwent PKP alone, and the studies by Claesson et al.  and Al-Marjan et al.  indicated that 71 and 66% of patients, respectively, underwent PKP alone.
Modern microsurgical techniques and the use of viscoelastic material has led to significant advances and decreased failure in corneal graft surgery .
Combined PKP with extracapsular cataract extraction was associated with graft survival rates that were comparable with those of simple PKP .
Comparing graft survival and final visual acuity between studies is difficult due to difference in population size and follow-up time. However, overall graft survival was 86% at the last follow-up compared with 88.9% at the last follow-up reported by Chaidaroon and Lewsakul , 82% reported by Rahman et al. , and 64% reported by Randleman et al. .
Final best-corrected visual acuity (after eliminating failed grafts) of 0.5 or better was achieved in 4.7% patients, 0.3-0.16 in 62.8% patients, and 0.1 or worse in 32.5% patients. Chaidaroon and Lewsakul  reported that final best-corrected visual acuity (after eliminating failed grafts) of 0.5 or better was achieved in 8.9% patients, 0.3-0.16 in 22.2% patients, and 0.1 or worse in 66.7% patients. Bhatti et al.  also reported that final best-corrected visual acuity (after eliminating failed grafts) of 0.5 or better was achieved in 33.3% patients, 0.3-0.16 in 41.7% patients, and 0.1 or worse in 25% patients.
Outcome of PKP in patients with keratoconus was good with 94.4% grafts remaining clear at final follow-up. Final best-corrected visual acuity of 0.5 or better was achieved in 5.6% patients. Randleman et al.  reported 87.5% clear grafts at final visit and final best-corrected visual acuity of 0.5 or better in 56.2% cases. Bhatti et al.  reported 88.9% grafts remaining clear at final follow-up and final best-corrected visual acuity of 0.5 or better was achieved in 55.6% patients.
Specific indications for corneal transplantation, in particular keratoconus and corneal dystrophies, have comparatively high survival rates .
Although we can add patients of corneal scar due to trauma and patients of corneal scar due to infection to be as one category named the corneal scar to be the leading indication in our study, the graft survival was also less than keratoconus (84.2%), and 5.2% patients had final best-corrected visual acuity of 0.5 or better. Randleman et al.  reported 66.7% clear grafts at final visit and final best-corrected visual acuity of 0.5 or better in 13.3% patients with corneal scar.
Bhatti et al.  also reported 78.6% clear grafts at final visit and final best-corrected visual acuity of 0.5 or better in 14.3% patients with corneal scar.
Corneal opacity after PKP occurred in seven (14%) eyes. Three (6%) eyes showed graft failure after the operation. Two (4%) eyes showed graft rejection and two (4%) had endophthalmitis. The graft failure rate was similar to that in the study by Chaidaroon and Lewsakul  (6.7%) and was low compared with that in the studies by Vail et al.  and Williams et al. .
This may reflect the improvement in educating the patient about the warning signs of graft rejection. In addition, an increased frequency of applied corticosteroid medication may have contributed to the overall decrease in allograft rejection .
However, we cannot judge through this study which preoperative diagnosis tended to have a higher incidence of graft failure because this study had a small sample size.
The patients with clear graft, who had less than 0.16 visual acuity, had as the main cause diabetic retinopathy (four eyes of 43 clear grafts) as an associated ocular diagnosis presumed to cause postoperative suboptimal visual acuity. Chaidaroon and Lewsakul  reported that the main cause of postoperative suboptimal visual acuity is age-related macular degeneration (three eyes of 40 grafts).
PKPs are sometimes beset by various complications. In our study, the rate of complications was highest in the corneal opacity due to infection group, four of 13 complicated cases, and lowest in the keratoconus group. Regarding individual complications, persistent epithelial defect and graft failure were the most frequent complications encountered (10 and 6%, respectively).
Persistent epithelial defect (epithelial defect for more than 8 days) in our study is similar to the studies of Shimazaki et al.  (12.0%) and Bhatti et al.  (13.3%).
The postoperative defect in epithelial layer may occur because of loss of epithelium during donor cornea storage, intraoperative trauma, or any kind of minute trauma during postoperative period, tear film abnormalities, ocular surface disorders, or the effect of medication (especially with preservatives) .
The incidence of endophthalmitis was considerably low (4%) in our study as compared with the study by Bhatti et al.  (6.7%) and was high as compared with rest of the world, Taban et al.  (0.2%). These cases were reported before 3 months of the follow-up. High-risk patients for PKP included eye rubbers and those who were unable to access eye care reliably .
Both of these cases shared above-mentioned factors and had unsatisfactory compliance and poor follow-ups. In addition, they belonged to remote rural areas of lower socioeconomic group with poor living conditions and inadequate hygiene. Graft failure is a rare but major complication of PKP. In our study, three (6%) cases were observed in comparison with 21 (2.7%) cases reported by Mead et al.  and two (6.7%) cases reported by Bhatti et al. . This was probably related to poor quality of donor material.
Graft rejection was observed in two (4%) cases. Bhatti et al.  reported two (6.7%) cases and similar rates are reported by Küchle et al.  and Al-Marjan et al. . Other complication encountered was recurrence of postherpetic corneal opacity, which is also reported in the literature.
This study showed that PKP is an effective procedure for corneal disease with poor vision. Visual outcome was good especially in cases of keratoconus. Similar studies in future will help in developing better understanding about the outcome of PKP in developing countries especially in Egypt.
| Conclusion|| |
PKP is a full-thickness, relatively easy surgical procedure to perform, and, with improvements both in surgical technique, material, and donor storage, the outcome is generally good. PKP is an effective procedure for corneal disease with poor vision. Visual outcome was good especially in cases of keratoconus. Diabetic retinopathy was the major cause of decreased visual acuity in patients with clear graft.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]