|Year : 2018 | Volume
| Issue : 2 | Page : 147-152
Changes in the tear film production and quality after 20- and 23-G vitrectomy: a prospective comparative study
Tamer Wasfy1, Elham A Gad2, Shaimaa S Soliman3
1 Department of Ophthalmology, Faculty of Medicine, Tanta University, Tanta, Egypt
2 Department of Ophthalmology, Faculty of Medicine, Benha University, Benha, Egypt
3 Department of Public Health and Community Medicine, Menofia University, Shibin El-Kom, Egypt
|Date of Submission||17-Nov-2017|
|Date of Acceptance||11-Jan-2018|
|Date of Web Publication||7-Jun-2018|
Department of Ophthalmology, Faculty of Medicine, Tanta University, 18 El Madares Street, Tanta 31511
Source of Support: None, Conflict of Interest: None
Background Dry eye is a common condition affecting many patients after different ocular surgeries. The recent technique of pars plana vitrectomy as 23- or 25-G vitrectomy has an overt advantage over the traditional 20-G vitrectomy in causing less damage to the conjunctival tissue.
Patients and methods This is a prospective randomized study, which enrolled 16 eyes that underwent traditional 20-G vitrectomy (group 1) and were compared with 15 eyes that underwent 23-G vitrectomy (group 2). Preoperative and postoperative (first day, first week, first month, and third month) Schirmer 1 (ST1) test and tear break-up time test (TBUT) were used to evaluate the tear film amount and quality. The postoperative symptoms and signs of dry eye were observed and compared in both groups.
Results No significant differences were found between the two groups regarding the mean age, sex distribution, comorbidities, and preoperative ST1 or TBUT tests. Both groups experienced excess tears at the first postoperative day. At the end of the first postoperative month, group 1 showed significantly lower values of ST1 and TBUT tests than group 2 (P=0.002 and <0.001, respectively), but by the end of the third postoperative month, there was no significant difference between the two groups regarding ST1 or TBUT test (P>0.05 for both tests). Patients in the 23-G group reported significantly less incidence of ocular pain and red eye at the first week and first month after surgery.
Conclusion 23-G vitrectomy has less damaging effects on the conjunctival tissue, reflected as less reduction in the tear film quantity and lower rates of dry eye, than the traditional 20-G method.
Keywords: 20 gauge, 23 gauge, pars plana vitrectomy, tear film, vitrectomy
|How to cite this article:|
Wasfy T, Gad EA, Soliman SS. Changes in the tear film production and quality after 20- and 23-G vitrectomy: a prospective comparative study. Delta J Ophthalmol 2018;19:147-52
|How to cite this URL:|
Wasfy T, Gad EA, Soliman SS. Changes in the tear film production and quality after 20- and 23-G vitrectomy: a prospective comparative study. Delta J Ophthalmol [serial online] 2018 [cited 2018 Jun 22];19:147-52. Available from: http://www.djo.eg.net/text.asp?2018/19/2/147/233938
| Introduction|| |
Machemer  introduced pars plana vitrectomy (PPV), which is now a common retinal procedure for treating some conditions such as diabetic retinopathy, macular holes, vitreous hemorrhage, infectious and inflammatory diseases of the retina, traumatic conditions, and cataract surgery complications ,,.
Since PPV was introduced, transconjunctival sutureless vitrectomy (TSV) became one of the most revolutionary developments in vitreoretinal surgery over the past few years. Fujii et al.  introduced the 25-G TSV in 2002, and 3 years later, according to the same surgical principle, Eckardt  developed the 23-G TSV.
In comparison with the traditional 20-G vitrectomy system, the 23-G system allows for smaller incision and spontaneously sealed and sutureless transconjunctival pars plana sclerotomies. This offers many advantages such as less surgical trauma, less postoperative inflammation, and rapid postoperative healing time . Discarding suturing may also shorten the total operative time .
Dry eye is a common ophthalmologic symptom that affects 10–15% of adults. This disease results from an increase in the tear film evaporation or a decrease in the tear production. The deepest layer of the tear film is mucinous and is produced by goblet cells, and this layer can be affected by chemical burns, Stevens Johnson syndrome, trachoma, cicatricial pemphigoid, and conjunctival trauma (including surgery) .
It has been known that vitreoretinal surgeries make conjunctival changes. There are few reports regarding prevalence and severity of dry eye after these surgeries. Heinrich et al.  reported the conjunctival histopathological changes in patients with previous vitreoretinal surgery and compared them with a normal group. Fibrosis in conjunctival stroma and reduction of goblet cells in eyes with previous vitreoretinal surgery or radiotherapy were found.
As the development of microincision vitrectomy surgery continues in this field, vitreoretinal specialists can rapidly review and cope with the most up-to-date information and have some surgical secrets as well ,.
This work aimed to assess and compare the tear film production and quality after 20- and 23-G vitrectomy. It opted a 3-month interval after the operation for reassessment of the tear film because at that time routine postoperative drops are stopped, and this time seems enough for healing of the tissue injury and inflammation induced by operation . Therefore, it seems that tear film test results would be more accurate by this time.
| Patients and methods|| |
A hospital-based prospective study was carried out. It included 32 eyes of 32 patients who underwent vitreoretinal surgery for retinal detachment (tractional or rhegmatogenous) and/or vitreous hemorrhage. The patients were randomly and equally assigned between the two groups using computer-based random number generator. A written informed consent was obtained from each participant. All the steps of the interview process and examination procedures were done in adherence to the guidelines of the declaration of Helsinki and were approval by the Ethical Committee of Tanta University.
Group 1 patients (20 G) underwent 360° periotomy followed by PPV using 20-G set with separate scleral and conjunctival closure using 7-0 vicryl sutures, whereas group 2 patients (23 G) underwent vitreoretinal surgery using 23-G vitrectomy with no periotomy or sutures at all. One patient from group 2 was lost to follow-up in the postoperative period and was excluded from the final analysis. All the surgeries were done successfully by an experienced vitreoretinal surgeon (T.W.).
All the patients were asked to stop all ocular medications one week before surgery except gatifloxacin 0.3% eye drops, which were instilled three times daily for 3 days before surgery. Tropicamide and/or phenylephrine eye drops were used to dilate the pupil half an hour before surgery. General anesthesia was used in all surgeries. After surgery, all the patients continued to use gatifloxacin 0.3% and prednisolone 1% eye drops four times/day in the first week, reduced to three times/day in the second week, then two times/ day in the third week, and lastly once daily in the fourth week. The conjunctival stitches in group 1 (20 G) were all removed by the end of first postoperative week. All patients were followed up at the end of the first postoperative day, first postoperative week, first postoperative month, and third postoperative month.
Apart from the routine ophthalmological examination and the routine investigations required for vitreoretinal surgery, all patients were subjected to Schirmer 1 test (ST1) and tear break-up time test (TBUT) 2 days before surgery and at all follow-up visits. Both tests were performed in a dimly lit room by a qualified nurse under the surgeon’s supervision. ST1 test was performed using Schirmer strips after removing excess tears from the lower fornix by a cotton-tipped applicator. The strip was bent at the notch and placed near the temporal lid margin (with the notch at the lid margin). The patients were asked to blink normally while the strip is in place which is then removed after 5 min and read at the point of maximum wetting. To perform TBUT, a fluorescein-impregnated strip wetted by nonpreserved 0.9% saline solution was placed in the lower conjunctival sac. The patients were asked to blink three times and then look straight forward without blinking while the tear film being observed under wide beam of the cobalt blue filter. The interval time between the last blink of the patient and appearance of the first dry corneal spot was measured and recorded as the TBUT.
The complaints of the patients were recorded and compared between both groups at different times of follow-up.
Data were analyzed by an IBM compatible personal computer with SPSS Statistical Package, version 23 (SPSS Inc., Armnok, New York, USA). Student’s t-test is a test of significance used for comparison of quantitative variables between two groups of normally distributed data. Paired t-test was used to compare different readings of normally distributed data in the same group. χ2-Test was used to study association between qualitative variables. Whenever any of the expected cells were less than five, Fischer’s exact test with Yates correction was used. McNemar’s test was used to evaluate multiple testing for paired categorical data measured only two times with only two outcomes.
| Results|| |
This study included 31 eyes of 31 patients. The mean age of the whole studied group was 55.25±7.05 years, with no significant difference in the mean age, sex distribution, or different comorbidities between the two groups ([Table 1]).
The comparison between the 2 groups regarding the preoperative ST1 showed no significant difference between them (P>0.05). At the first postoperative day, group 1 (20 G) showed significantly higher mean value of the ST1 (13.56±1.45 mm) than group 2 (23 G) with 12.13±0.91 mm (P=0.003). This continued till removal of the conjunctival stitches by the end of first postoperative week, as group 1 had mean ST1 value of 11.93±1.06 mm and group 2 had a value of 11.00±1.06 mm (P=0.02). By the end of the first postoperative month, group 1 showed significantly lower values of ST1 test (9.32±0.95) than group 2 (10.46±0.99), with P value of 0.002. However, by the end of the third postoperative month, there was no significant difference between the two groups regarding ST1 test (P=0.33) ([Table 2] and [Figure 1]).
|Table 2 Schirmer test and tear break-up time test results in the studied groups|
Click here to view
The preoperative TBUT test showed no significant difference between both the groups. By the end of first postoperative day, group 1 had significantly lower TBUT test result (8.18±1.55 s) than group 2 (10.40±1.35 s), with P value less than 0.001. This significant difference continued till the end of the first postoperative month (P=0.04), but then by the end of the third postoperative month, there was no significant difference between the two groups (P>0.05) ([Table 2] and [Figure 2]).
Within-group comparisons showed that inside each group the case was somewhat different. Group 1 showed significantly higher ST1 results at the end of the first day and first week after surgery than the preoperative level (P<0.001 and 0.001, respectively). At the end of first postoperative month, this group showed significantly lower ST1 than the preoperative level (P=0.002), but by the end of this study (third postoperative month), ST1 level in this group almost returned to the preoperative level with no significant difference between these two time measurements (P=0.06).
Group 2 had only significantly higher ST1 level at the first postoperative day than the preoperative level (P<0.001). There was no significant difference between the ST1 levels at all the following follow-up visits compared with the preoperative level ([Table 2] and [Figure 1]).
Regarding TBUT test, it was significantly lower at the first postoperative day after surgery than the preoperative level in both groups. In group 1, this significant decrease in the TBUT from its preoperative level continued till the end of the first postoperative month (P=0.02) but then disappeared at the third postoperative month (P=0.07). On the contrary, in group 2, the TBUT did not show any significant difference at the first postoperative week, first postoperative month, or third postoperative month compared with the preoperative level ([Table 2] and [Figure 2]).
As shown in [Table 3], all patients in group 1 experienced excess tears and pain in the first postoperative day, whereas less than half of the patients in group 2 experienced the same complaints (P<0.001). These complaints significantly improved in both groups from the first postoperative week (time of stitches removal in group 1). However, this improvement was greater in group 2, as 80% of the patients were free of excess tears and ocular pain by the end of the first postoperative week.
| Discussion|| |
Many patients complain of eye discomfort after vitreoretinal surgeries. This can be caused by many reasons, and tear film abnormality is a major one. This study compared the effects of conventional 20-G vitrectomy and 23-G vitrectomy on the amount and quality of the tear film.
Many studies have been published to demonstrate the changes in tear film after eye surgeries like phacoemulsification or strabismus surgery. Liu et al.  compared the changes in tear film after phacoemulsification surgery in diabetic and nondiabetic patients and found significant decrease in the tear film production in the first postoperative day in diabetic patients than nondiabetics which then returned to the normal level on the 180th postoperative day in both groups. Khanal et al.  compared the tear physiology among three groups of patients after phacoemulsification surgery: a group on tear substitutes, a group on saline, and a control group without any eye drops. They found significant increase in the tear film evaporation immediately after surgery in all groups with no effect of saline and tear lubricants on the tear physiology after surgery. In the same context, Oh et al.  reported no difference between the mean postoperative and preoperative ST1 in patients who underwent phacoemulsification surgery, although having significant decrease in the TBUT at the first postoperative day than the preoperative level, but this had nearly returned to the preoperative level after 1 month of surgery. However, strabismus surgery did not seem to have an adverse effect on the tear film secretion or stability according to what was reported by Chang et al. .
Vitreoretinal surgeries are somehow different from phacoemulsification and strabismus surgery. There is the conventional technique that still uses the 20-G vitrectomy, which is done in many parts of the world, and there are also the uprising suturless techniques using the 23- or the 25-G vitrectomy trocars. In the current study, the group of patients who had the 20-G vitrectomy (group 1) experienced postoperative excess lacrimation because of the irritating effect of the 7/0 vicryl sutures. This was evident by the significant increase in the mean ST1 level in group 1 (15.50±2.42 mm) than in group 2 (12.13±0.91 mm) in the first postoperative day, which continued till the first postoperative week and first postoperative month and disappeared by the end of the third postoperative month as both groups almost returned to the preoperative level.
To study the stability of the tear film, we used the TBUT. Both groups had significant reduction in the TBUT at the first postoperative day than the preoperative time. This decrease in TBUT disappeared in group 2 before the end of the first postoperative week but continued in group 1 and did not disappear till the first month after surgery.
These results were in agreement to the study published by De Zanet et al. , who studied nine eyes that underwent 25-G vitrectomy and seven eyes that underwent 20-G vitrectomy using TBUT and ST1 tests for 7 days after surgery and found a significant increase in the mean corneal fluorescein staining in all patient with 20-G vitrectomy and a decrease in TBUT score in half of them (<5 s). However, they did not find any statistically significant difference in ST1 values between the two groups.
A very recent study was done by Khalil et al.  to compare the changes of ST1 after both 20-G (20 patients) and 23-G vitrectomy (22 patients). They found a significant decrease in ST1 test results at 1 and 3 months after surgery compared with baseline or the fellow unoperated eye. They found no significant difference between the two groups at 1 month after surgery. However, patients with 20-G vitrectomy had significantly more decrease in the ST1 results than patients with 23-G vitrectomy.
In addition, Banaee et al.  published a study of 75 eyes from the year 2005 to 2007 who all underwent 20-G vitrectomy and found that dry eye symptoms and abnormal results of ST1 and TBUT were more common in patients who underwent scleral depression especially for extensive depression and usage of cotton-tipped applicator. They found also significant positive correlation between the development of dry eye and the extent of the periotomy.The within-group comparisons showed that group 1 had significant increase in the tear production during in the first postoperative day and postoperative week than the preoperative level, whereas group 2 had only significant increase in lacrimation in the first postoperative day and almost returned to the preoperative level by the end of the first postoperative week.
In the present study, the 23-G vitrectomy group reported less ocular pain and irritation than the 20-G group. The same was observed by De Zanet et al. , as only 21% in their 25-G group had dry eye symptoms at postoperative day 7.
Financial support and sponsorship
This research was all financially supported by the authors.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]