|Year : 2018 | Volume
| Issue : 2 | Page : 113-118
Vitreous loss-causes, associations, and outcomes: Eight-year analysis in Melaka Hospital
Thanigasalam Thevi1, Adinegara Lutfi Abas2
1 Department of Ophthalmology, Hospital Melaka, Melaka, Malaysia
2 Department of Community Medicine, Melaka Manipal Medical College, Melaka, Malaysia
|Date of Web Publication||28-May-2018|
Department of Ophthalmology, Jalan Mufti Haji Khalil, Melaka 75400
Source of Support: None, Conflict of Interest: None
| Abstract|| |
BACKGROUND: Cataract surgery is associated with a variety of complications, one of which is vitreous loss. Doctors and policymakers should be aware about the precipitating factors, associations, and expected outcomes of vitreous loss. This study was, therefore, undertaken to set guidelines to improve the visual outcomes of patients.
MATERIALS AND METHODS: A retrospective 8-year analysis was conducted from 2007 to 2014 using the national eye database. Demographic features, ocular comorbidities, grade of surgeon, type of surgery, and the associations with the occurrence of vitreous loss, and the final visual outcomes of these patients were studied.
RESULTS: Out of 12,992 eyes, only 3.2% had vitreous loss, mostly aged <40 years. Pseudoexfoliation was the only ocular comorbidity causing vitreous loss. Medical Officers and Gazetting Specialists got more vitreous loss compared to specialists. Intracapsular cataract extraction, phaco convert to extracapsular cataract extraction (ECCE), ECCE, and phaco all had a significant vitreous loss. Vitreous loss was the most significant intraoperative complication causing poor vision and resulted in impaired or poor visual outcome.
CONCLUSION: Vitreous loss occurred in almost all types of cataract surgeries, especially by junior surgeons, among those aged <40 years and significantly caused poor visual outcome compared to other complications. Pseudoexfoliation had higher occurrence of vitreous loss. Vitreous loss patients had impaired/poor visual outcome due to preexisting comorbidity and astigmatism. Patients at risk and junior surgeons should be closely monitored to improve outcomes. Further studies need to be done to see why and when the vitreous loss occurred.
Keywords: Associations, causes, outcomes, vitreous loss
|How to cite this article:|
Thevi T, Abas AL. Vitreous loss-causes, associations, and outcomes: Eight-year analysis in Melaka Hospital. Oman J Ophthalmol 2018;11:113-8
| Introduction|| |
Cataract, the leading cause of blindness in Malaysia and Southeast Asia, was the most common ailment seen in eye clinics in both urban and rural population.,,, Cataract surgery complications can be detrimental to vision. Vitreous loss has been known to cause further complications such as retinal detachment (RD) and cystoid macula edema. Doctors and policymakers should be aware of the precipitating factors, associations, and outcomes of visual loss in our settings. This study was done to set guidelines to improve the visual outcomes of patients undergoing cataract surgeries.
Melaka has a population of 860,000. Melaka Hospital, with 806 beds is the only multispecialty government hospital with cataract services in the state. Most patients undergo surgery here due to free costs to civil servants and pensioners and cheaper costs for others. Civil servants and pensioners are reimbursed for the cost of intraocular lenses (IOLs).
| Materials and Methods|| |
A retrospective analysis of cataract surgeries from the cataract surgery registry (CSR) covering 8 years from 2007 to 2014 was done after obtaining permission from the Malaysian research ethics society. Data were obtained from the national eye database (NED). NED is a service supported by the ministry of health and has several registries, one of which is the CSR. Data are keyed in by medical officers doing preoperative assessment of patients and medical officers performing/assisting in the operation theaters. Postoperative outcomes are keyed in by optometrists. All findings keyed in the computer are based on the written notes of patients by optometrists and doctors.
All intraoperative complications such as posterior capsule rupture (PCR), vitreous loss, zonular dehiscence, dropped nucleus, suprachoroidal hemorrhage, and central corneal edema were noted. Details of vitreous loss were studied. Patients in the NED with vitreous loss were those who had presence of vitreous during any stage of the surgery. These cases may have been due to either PCR or zonular dialysis. Demographic features of these patients such as age, ethnicity, and gender were noted. Melaka population consists of Malays, Chinese, Indians, and Eurasians. Foreign nationals from Indonesia, Bangladesh, Vietnam, Cambodia, and India also reside temporarily while being employed here.
Ocular comorbidities of patients with vitreous loss and the associations were studied. Ocular comorbidities recorded were pterygium involving the cornea, corneal opacity, glaucoma, chronic uveitis, and pseudoexfoliation.
The grade of the surgeon operating whether a specialist, gazetting specialist or medical officer were noted. The type of cataract surgery done was noted to study which technique caused more vitreous loss compared to the other. The techniques were extracapsular cataract extraction (ECCE), phacoemulsification (phaco), phaco converted to ECCE, lens aspiration, and intracapsular cataract extraction (ICCE). All combined surgeries were noted to study which combinations caused vitreous loss.
The final visual outcome in patients with vitreous loss was studied. The reasons for not obtaining good vision were looked into. Vision was categorized into good (6/6–6/12), impaired (6/18–6/36), and poor (6/60 and worse). Visual outcome was taken as the best-corrected vision by refraction performed by hospital optometrists at 12 weeks postoperatively which is the standard set by the NED steering committee.
The data were analyzed with IBM SPSS Statistics for Windows Version 20.0 (IBM Corp, Armonk, NY. Released 2011). The global Chi-square and Fisher's exact test were used to determine the possible relation between two categorical variables. P < 0.05 was considered statistically significant.
| Results|| |
A total of 12,992 eyes underwent cataract surgery from 2007 to 2014 but only 6.1% had intraoperative complications. Some had more than one intraoperative complication during surgery. PCR was the highest complication with 623 eyes (4.8%) followed by vitreous loss with 411 eyes (3.2%). A total of 411 (3.2%) eyes had vitreous loss in this study [Figure 1]a. Due to some missing data, only available data was analyzed in various sections of the study. [Table 1] shows that gender (P = 0.14) was not significantly associated with vitreous loss, but age (P = 0.016) and ethnicity (P = 0.035) were significantly associated with vitreous loss. The highest percentage of vitreous loss was seen in those aged below 40 years with 18 out of a total of 328 eyes (5.5%) and among other races such as Kadazan, Iban, and Orang Asli with 6 eyes out of a total of 93 eyes (6.5%). The main and only significant ocular comorbidity associated with vitreous loss was pseudoexfoliation as observed in 13 eyes out of a total of 149 eyes (8.7%) (P = 0.001). Other comorbidities associated with vitreous loss were corneal opacity with 30 eyes out of a total of 863 eyes (5.3%), pterygium involving the cornea with 7 eyes out of a total of 194 eyes (3.6%), and glaucoma with 30 eyes out of a total of 863 eyes (3.5%) as shown in [Table 2]. No case of uveitis had vitreous loss.
|Figure 1: (a and b) Intraoperative complications reasons for not obtaining good visual acuity|
Click here to view
Gazetting specialists (7.0%) and medical officers (6.9%) both had significantly higher rates of vitreous loss compared to specialists (2.4%) (P< 0.001) as seen in [Table 2]. [Table 2] shows that ECCE, phaco and phaco converted to ECCE were all associated with vitreous loss (P< 0.001). Only lens aspiration was not associated with vitreous loss (P = 0.188). Vitreous loss resulted in significant amount of eyes getting impaired vision with 82 eyes out of a total of 1306 eyes (6.3%) (P< 0.001) and poor vision with 37 eyes (7.7%) (P < 0.001) as seen in [Table 2].
Vitreous loss resulted in a significantly higher rate of visual poor outcome with 37 eyes out of a total of 328 eyes (11.3%) compared to other intraoperative complications noted in 442 eyes out of a total of 10666 eyes (4.1%) [P< 0.001; [Table 2]. The other intraoperative complications that we compared vitreous loss with were PCR, suprachoroidal hemorrhage, and dropped nuclei. Most patients did not get good vision due to preexisting ocular comorbidity.
High astigmatism with 18 eyes (4.4%), cystoid macular edema (CME) with 6 eyes 1.5%, posterior capsular opacity with 3 eyes (0.7%), and corneal decompensation with 3 eyes (0.7%) accounted for the poor vision following vitreous loss as elaborated in [Figure 1]b. There were no cases of RD or IOL subluxation or dislocation.
| Discussion|| |
This was a retrospective analysis of cataract surgeries performed on patients admitted into hospital Melaka covering 8 years from 2007 to 2014. We noted vitreous loss occurring among patients aged <40, among surgeries mainly performed by junior surgeons and occurring in almost all types of cataract surgeries. In addition, preexisting ocular comorbidity such as pseudoexfoliation was associated with vitreous loss. We further observed the presence of vitreous loss to be associated with poor visual outcome postoperatively.
The highest percentage of vitreous loss was seen in those aged <40 years. The number of patients aged <40 undergoing cataract operation was small (328) and therefore showed a high percentage of 18 patients with vitreous loss. For vitreous loss to occur, there must first be either a PCR or zonular dehiscence. Posterior capsule tear with vitreous loss (1.4%) was the major complication in an analysis of 1,000 cases of phacoemulsification  PCR and vitreous loss recognized early can prevent a nucleus dropping. Recognizing a small PCR and managing appropriately may prevent the tear enlarging and causing vitreous to prolapse.
Pseudoexfoliation was the most common ocular comorbidity and was significantly associated with vitreous loss in our study. Other studies have also found pseudoexfoliation to be associated with vitreous loss.,,
In pseudoexfoliation, there can be zonular weakness and the pupil may not dilate well. However, Thanigasalam et al. did not find any correlation between pseudoexfoliation and PCR in phaco. Though cornea opacity was associated with vitreous loss, it was not significant. The cornea opacity was probably hampering the view of the surgeon for the details of the anterior chamber. We could not find any literature showing cornea opacity association with vitreous loss.
A significantly higher rate of vitreous loss was seen among more junior surgeons. Medical Officers (P< 0.001) as well as Gazetting specialists (P< 0.001) had higher rates of this complication. A medical officer has a basic MBBS degree and may or may not be in postgraduate training for ophthalmology. A Gazetting specialist is one who has passed the postgraduate Ophthalmology examination but is under supervision of a senior specialist who assesses the fitness of the specialist to treat and operate patients independently during the period of gazettement, which is a minimum of 6 months. There is selection bias to a certain extent here as cases that are listed as potentially difficult such as pseudoexfoliation or subluxated lenses are given to specialists to do. However, the grade and experience of specialists differ; some are very senior while others have recently passed the examination. Experience was found to improve the incidence of vitreous loss. In a study of 3,000 phacos by a senior consultant, the initial rate of vitreous loss was 4.0% in the first 300 cases falling to 0.7% in the last 300 cases. Other studies have also found that intraoperative complications of cataract surgeries improved with experience. In a multicenter audit of 55,567 cases, risk indicators for PCR/vitreous loss/both included trainee surgeons performing surgery. It would have been interesting to know at which point of time the vitreous loss occurred. A study in the same hospital by Thanigasalam et al. found that PCR occurred mostly during cortex removal by consultants and during segment removal by specialists.
Almost all techniques of cataract surgeries were significantly associated with vitreous loss. ICCE (P< 0.001) and phaco convert to ECCE (P< 0.001) had highest rates of vitreous loss.
Number of ICCE cases were small (78) compared with number of phaco convert to ECCE (185) accounting for the high percentage in ICCE cases.
Phaco convert to ECCE were those cases where initially phaco was commenced, but for some reasons (extended capsulorhexis, difficulty sculpting/cracking, etc.,) it was converted to ECCE. Vitreous was present only after the case was converted from phaco to ECCE. ECCE (4.4%) and phaco (2.1%) were also significantly associated with vitreous loss. Only lens aspiration was not significantly associated with vitreous. We could not find a single study comparing all techniques of cataract surgery with the occurrence of vitreous loss. Allinson et al. found that residents learning phaco had a higher rate of vitreous loss compared to residents learning ECCE. The incidence of vitreous loss between ECCE/Blumenthal versus phacoemulsification techniques (P< 0.05) in a study by Kothari et al. Thevi et al. found that ICCE and phacoemulsification converted to ECCE were significantly associated with more complications (P = 0.001).
The occurrence of vitreous loss significantly affected the visual outcome, and it was the most significant complication causing poor vision (P< 0.001). More patients with vitreous loss got impaired vision (P< 0.001) and poor vision (P< 0.001) compared to good vision. After excluding the most common cause which was preexisting ocular comorbidity, high astigmatism and CME accounted for most cases which did not obtain good visual acuity. Frost et al. also found significantly poorer outcomes in cases of vitreous loss, with a higher incidence of CME. The vitreous loss has to be managed by enlarging the wound-whether by sponge or automated vitrectomy. Due to enlargement of the wound – this can contribute to the Astigmatism. High Astigmatism has been reported as a cause for poor outcome. Further prospective studies need to be done to see why the Astigmatism could not be corrected? Were they due to irregular Astigmatism? Was some other underlying pathology such as subclinical cystoid macula edema not detected due to unavailability of OCT?
In a study of vitreous loss among residents by Blomquist and Rugwani  good vision of better than 20/40 was obtained.
In 77%, but after excluding the preexisting ocular comorbidities, 91% had a vision of 20/40 or better. CME accounted for 6% of poor vision.
| Conclusion|| |
Vitreous loss occurred in almost all types of cataract surgeries, especially in patients aged <40 years, done by more junior surgeons, resulting in impaired and poor visual outcome mainly due to preexisting ocular comorbidity, astigmatism, and cystoid macula edema. It was the most significant intraoperative complication causing poor vision. We suggest that further studies be done to look at why and when vitreous loss occurred, for example, an unrecognized PCR/zonular dialysis, to reduce this complication. We suggest that prospective studies be done in the future to eliminate selection bias.
Strength and limitations
The study involved a large number of cases from the NED and analyses of various factors. The point of occurrence/recognition of vitreous loss and subsequent management should be studied in the future, to minimize the occurrence of vitreous loss and the further complications that occur.
We thank the Director General of Health for granting permission to publish the study. We thank the Director of CRC Dr. Goh PP and Coordinator of NED Teng KM for providing the data.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]