Corneal epithelial defect after pars plana vitrectomy.

AIM: This study aims to study the incidence of corneal epithelial defect (CED) after pars plana vitrectomy (PPV) and associated patient-related risk factors. The incidence of other immediate postoperative complications was also in the scope of this study.
DESIGN: Retrospective descriptive case series study.
METHODS: Review of electronic medical records of all patients who underwent PPV alone or combined with cataract surgery and/or scleral buckle in a tertiary hospital by one retinal surgeon. All demographic data, surgery notes, and immediate postoperative findings were obtained for all patients.
RESULTS: The cohort of the included cases was composed of a total of 168 procedures that were performed in 121 eyes of 106 patients over 5 years. CEDs occurred in 19 eyes (15.7%) of 19 patients (17.9%). Males were affected more than females (90% vs. 10%). Patients with postoperative CED were found to have longer duration of surgery when compared to patients without postoperative CED (P = 0.0038). All cases of CED had a complete resolution of the defects after supportive therapy. Immediate intraocular hypertension (IOH) was found in 30 eyes (24.8%). IOH was controlled in all cases with medical therapy only. Post-PPV immediate complications, other than CED and IOH, occurred in 10.7% of the eyes. These included vitreous hemorrhage, choroidal detachment, corneal edema, anterior chamber fibrin, and hyphema.
CONCLUSION: Development of CED is not uncommon after PPV. This complication is more common in males and may be related to prolonged duration of surgery. It also develops more in older patients. CED after PPV can be managed with conservative treatment with good outcome.

Introduction

Corneal complications after intraocular surgeries are well known. Theoretically, they can occur more often after procedures involving anterior segment of the eye. Such of these complications are corneal edema, Descemet's membrane abnormalities, endothelial dysfunction, corneal epithelial abnormalities, and infectious keratitis.

The occurrence of corneal epithelial defects (CED) after pars plana vitrectomy (PPV) is not well described in the literature. Thus, it is a very important and interesting area to investigate since it has some consequences such as visual rehabilitation and adjustment of postoperative therapy. The incidence of CED after PPV may reach up to 23.8%.[1234] The mechanism of this disorder is not well understood. Diabetes mellitus (DM) had been known to be a risk factor in the development of postoperative corneal complications.[5] The mechanism behind that is the abnormal corneal histopathological structure in diabetic patients.[5678] Other risk factors that can lead to the development of postoperative CED might be classified into intrinsic and extrinsic. Intrinsic factors include patient-related disorders such as diabetic keratopathy, corneal dystrophies, corneal degenerations, and limbal stem cell deficiency. Extrinsic factors are mechanical (e.g., trauma by instruments) or chemical (e.g., disinfectants and agents used intraoperatively). Other extrinsic factors are the duration of the surgery and type of procedures, for example, vitrectomy and phacoemulsification. CED occurs more frequently when the contact viewing system, during vitrectomy, is used rather than the noncontact viewing system.[1]

Some patients might develop persistent CEDs (PCEDs) after PPV. The incidence of PCED was found to be up to 4.8% after PPV.[4910] Risk factors that are attributed to the development of PCED are DM, intraoperative lensectomy, usage of perfluorocarbon liquid, C3F8 gas tamponade, and a training surgical assistance.[910] Those patients usually have undesirable postoperative visual outcome.

The main purpose of this study was to find out the incidence of CEDs after PPV. Determination of associated risk factors was also investigated in this study.

Methods

This study was conducted by performing a retrospective chart review. Ethical approval for the study was obtained from the Institutional Ethics Committee. Data of patient demography, surgery notes, and immediate postoperative findings were collected. All patients (children and adults) who underwent PPV were included in the study. Inclusion criteria were patients who underwent PPV alone or combined with phacoemulsification and/or scleral buckle. Patients who had intraoperative trauma or corneal epithelial debridement were excluded from the study. All surgeries were performed by one retina surgeon at Sultan Qaboos University Hospital. All patients were admitted to the ophthalmology ward. Preoperative eye drops included dilating eye drops (tropicamide 1% and cyclopentolate 1%) and iodine 5% eye drops just before the surgery. The cases were performed under either general anesthesia or local retrobulbar anesthesia. The binocular indirect ophthalmoscope noncontact viewing system was used in all cases. During each procedure, methylcellulose gel (Methocel® 2%) was used as a wetting agent for the cornea. At the end of the surgery, all patients received a subconjunctival injection of a mixture (total of 1 ml) of dexamethasone (2 mg in 0.5 ml) and gentamicin (20 mg in 0.5 ml). The operated eye was then patched after instilling fusidic acid and atropine 1% eye drops until the next day. All patients were evaluated by the surgeon next day morning in the ward with a slit-lamp examination. Patients, who were found to have CED, were treated with antibiotic eye drops and/or bandage contact lenses. High intraocular pressure (IOP) was another important postoperative finding in those patients. High IOP was defined as a pressure more than 21 mmHg by applanation tonometry. Antiglaucoma eye drops with or without oral carbonic anhydrase inhibitors were used in patients with high IOP.

Data analysis of the study was performed with Chi-square test. A statistical comparison between the group with CED and the group without CED was done.

Results

The covered period of the study was from November 1, 2009, to March 31, 2015. A total of 168 procedures on 106 patients (121 eyes) were performed [Table 1]. The average age of all patients was 54.2 years (range 7–89 years).

Table 1

Demographic data of the patient cohort

Noncontact viewing system, to visualize retina, was used during all procedures. Out of the 168 total procedures, the CED occurred after 21 procedures (12.5%). The involved number of eyes with CED was 19 (15.7%) of 19 patients (17.9%).

The average time for healing of the CED in cases of our study was 2.9 days (range 1–12 days). The treatment for the CED included antibiotic eye drops and/or bandage contact lenses. All cases had a complete healing, and there were no cases of PCED.

A comparison was performed between eyes that developed CED and eyes that did not develop it [Table 2]. Furthermore, the occurrence of CED compared to age group is illustrated in Figure 1.

Table 2

Comparison between eyes with corneal epithelial defect and eyes without corneal epithelial defect

Figure 1

Chart of patients who developed corneal epithelial defect and their age group

Postoperative complications, other than CED, are summarized in Table 3. These complications were observed in day 1 after the PPV.

Table 3

Incidence of immediate (24-h postoperative) postpars plana vitrectomy complications

The overall immediate complications after PPV occurred in 62 eyes (51.2% of total eyes; 36.9% of total procedures). High IOP in the 1st postoperative day was another adverse event that occurred after PPV. It occurred in 30 eyes (24.8%) of 27 patients (25.5%). The male patients constituted 17 (63%) out of those 27 patients. Only two eyes out of those 30 eyes had intravitreal steroid injection during the surgery. Preoperative glaucoma was present in seven eyes out of those 30 eyes.

Discussion

The two most common observed immediate postoperative complications after PPV in our study were CEDs (15.7%) and high IOP (24.8%). Other complications also occurred but less common (10.7%), as shown in Table 3.

In general, corneal complications after PPV are well known. They occur in up to 55.4% of postoperative cases.[91011] CEDs are one of those complications. Some studies showed that the contact lens viewing system carries more risk for the development of CED after the PPV.[1] Another study compared different agents used to wet the cornea during PPV procedures. The results revealed that viscoelastic agents are better agents than balanced salt solution (BSS) for wetting the cornea.[2]

The mechanism of development of CED is not well understood. However, intrinsic and extrinsic factors play an important role in the development of CED after PPV. Since all cases in our cohort of patients had PPV with the use of noncontact viewing system, other factors could be the reason behind CED development. Intrinsic factors, which are related to the patient including diabetic keratopathy, corneal dystrophies, and degenerations, are possible causes. However, a prospective study would be a better way to evaluate that. On the other hand, one of the interesting findings in our study is a higher trend of occurrence of CED in males than females (90% vs. 10%, respectively). Thus, male gender could be considered as a risk factor to develop CED after PPV surgery. In the group of patients, who did not develop CED, the males and females were 60% and 40%, respectively. There was also a noticeable proportional relationship between the development of CED and older age. This might be expected as aging can provoke more degenerative changes in the cornea as other parts of the body. In addition, during PPV procedures, different agents were used in all patients such as iodine 5% eye drops as a disinfectant, Balanced Salt Solution Plus (BSS+) as intravitreal irrigation fluid, and methylcellulose gel as a wetting agent. However, the development of CED occurred in some eyes but not all. A trend was observed between the development of CED and use of silicone oil as an intraocular tamponade. Interestingly, the type of procedure (PPV alone or combined with other procedures) and the use of intravitreal triamcinolone did not carry any significant impact in the development of CED. As DM was known to be a risk factor in the development of postoperative corneal complications, we did not find a correlation between post-PPV CED and the DM. A larger sample size might be required to investigate that.

Duration of the eye surgery was found to have a significant risk in the development of CED after PPV. The longer the procedure, the more risk to develop CED after surgery. This could be as a resultant of using more chemical agents whenever the procedure lasts longer.

During the same period of our study, a pilot study with unpublished data showed that development of CED after cataract surgery was only 2.2%. This difference in the incidence of development of CED between PPV and cataract surgery was not surprising since cataract surgery lasts shorter than PPV and the used wetting agents are different.

Immediate postoperative complications occurred very often. The CED and high IOP occurred in 49 eyes (40.5%) of all eyes [Table 3]. All cases of CED were treated conservatively with antibiotic eyes drops with or without bandage contact lens. All of them had completely healed CED. The average healing period was 2.9 days. There was no single case of PCED, which is defined as CED lasting more than 2 weeks after PPV despite treatment.[1012] In addition, all cases of high IOP were successfully treated with antiglaucoma medical therapy and were well controlled thereafter.

This study that we performed provided interesting findings. However, it has some limitations such as a retrospective design which compromise obtaining important information especially preoperative ocular findings. Larger sample would provide more accuracy in data analysis and conclusion.

Conclusion

PPV is a major intraocular procedure. It carries some risks to develop postoperative complications. CED and high IOP were the most common post-PPV complications. However, these two complications are not serious and can be managed medically with good outcome. In this study, additional risk factors for the development of post-PPV CEDs were found which are male gender and longer duration of surgery. Patients with age group of 50–70 years are more prone to develop CED after PPV.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.