Outcomes and Determinants of Posterior Dislocated Intraocular Lens Management at a Tertiary Eye Hospital in Central Saudi Arabia.

PURPOSE: The aim of this study is to evaluate the determinants of visual outcomes, complications after managing the posterior dislocated intraocular lens (IOL).
METHODS: Patients with posterior dislocated IOL managed between 2002 and 2016 in our institute were reviewed. Ocular status and causes for dislocation were noted. Success was defined as uncorrected visual acuity (UCVA) of 20/20-20/200 at the last follow-up. The risk factors were associated with the success.
RESULTS: Of the 79 eyes with posterior dislocated IOL, 40 (50.6%) eyes had vision <20/400 at presentation. Glaucoma and retinal detachment were present in 12 (15.2%) and 5 (6.3%) eyes. IOL was removed from 33 (41.8%) eyes. Secondary IOL was implanted in 25 (31.6%) eyes, and IOL was repositioned in 19 (24.1%) eyes. The median duration of follow-up was 2.1 years. The final UCVA was "20/20-20/60" and ">20/200" in 45 (57%) and 14 (17.7%) eyes. The main causes of Severe visual impairment (SVI) included glaucoma (5), corneal decompensation (5), retinal detachment (4), and macular edema (3). Young age (P = 0.02), late IOL dislocation (P = 0.005), primary IOL implant (P < 0.01), SVI (P = 0.09), IOL removal (P = 0.06), and no glaucoma at presentation were significantly associated to the success. Late IOL dislocation (P = 0.05) and no glaucoma (P = 0.05) were independently associated to the success.
CONCLUSION: The management of the dislocation of IOL had promising visual outcomes. Glaucoma and early dislocation predict poor vision after dislocated IOL management. Close monitoring is needed to manage complications. Copyright:

Introduction

Acataract is the leading cause of curable visual impairment.[1] To provide a high level of vision-related quality of life, intraocular lens (IOL) implant during cataract surgery is a routine procedure.[23] Unfortunately, due to systemic like diabetes or ocular comorbidities, IOL sometimes dislocates and need prompt management.[4]

The incidence of dislocation of the IOL implant ranges between 0.2% and 2%.[45] Dislocation of IOL within capsular bag often take place in the eye with pseudoexfoliation (PEX), retinitis pigmentosa (RP), trauma, history of vitrectomy, and high myopia.[67] The dislocation of IOL outside capsular bag is noticed in cases with PEX or mature cataract.[6] The risk of this serious complication is less common. Availability of vitreo-retina subspecialists results in fewer long-term complications and promising visual outcomes after managing dislocated IOL.[8] In a teaching institute like ours, referred cases are managed, and often trainee ophthalmologists manage cataract cases, dislocated IOL are managed more frequently.

The prevalence of PEX among cataract cases in Arab countries has been reported high.[9] Therefore, it would be interesting to study the causes and management outcomes of the dislocated intraocular lens.

We present the outcomes of posterior dislocated IOLs implant managed and their determinants at our institution in Central Saudi Arabia between 2000 and 2016.

Methods

The Institution Research Board approved of this study (1260– R). Since this was a review of the health record, and patient consent was waived. All patients managed for posterior dislocated IOL between 2000 and 2016 were included in this review. The personal identity of the patient was delinked from the remaining data for maintaining their confidentiality. Those with at least 6 months of follow-up after the management of posterior dislocated IOL were included in our study.

Two vitreoretinal specialists were the field investigators. The ICD10 code for dislocated IOL (T85.22XA) was used to identify cases with this provisional diagnosis. The demography of these patients included age, gender, and eye involved. The systemic aliments like diabetes PEX syndrome and ocular profile at presentation were based on the history and eye examination. The history included previous ocular surgery, cataract surgery, ocular trauma, treatment for PEX syndrome, and diabetes. The uncorrected visual acuity (UCVA) for distance was assessed using Snellen's chart projector at 6 m. If the patient could not recognize the top letter, vision was retested at 3 m distance. The anterior segment was evaluated at presentation and at different follow-ups using the slit-lamp biomicroscope (Topcon, USA). The ciliary injection, status of the cornea, cells in the anterior chamber, evidence of active or old uveitis, PEX, evidence of laser iridectomy, etc., were noted. The intraocular pressure (IOP) was measured after anesthetizing the cornea. Applanation tonometer mounted on the slit lamp was used to measure IOP.

The posterior segment was evaluated using + 20D and + 90D Volk lens and slit-lamp biomicroscope. We documented evidence of PEX, uveitis, status of the macula, cells in vitreous, posterior vitreous detachment, retinal breaks, retinal detachment, and status of optic disc in relation to inflammation and glaucoma.

A-scan and B-scan ultrasonography was carried out to determine the exact location of IOL in PC and other pathologies of vitreous and retina.

The IOP was controlled using topical anti-glaucoma medications. With informed written consent for the surgery and adequate precautions for avoiding infection, IOL removal done through posterior approach by vitreoretinal specialists, the surgical approach was based on the surgeon's preference. Using three-port pars plana vitrectomy (PPV) with the aid of perfluorocarbon injection which was then removed. The IOL was either removed or repositioned through limbal incision. Complications and their management during the surgery and in the early postoperative period were documented from the operative notes. The follow-up was at 3 months, 6 months, and at last follow-up visit. Status of IOL, glaucoma, and inflammation were documented along with UCVA at each follow-up. The visual acuity (VA) was further grouped as “functional normal vision” if it was “20/20–20/60.” Moderate visual impairment included eyes with vision “<20/60–20/200.” Severe visual impairment (SVI) was considered if vision was “<20/200–20/400.” Eyes with vision “<20/400” were termed as blind.

The date and last follow-up uncorrected VA was noted. The duration of follow-up was determined. The anatomical success was defined as the stabilization of IOL at the last follow-up. The functional success was defined as vision >20/60 at the last follow-up.

The data were collected using pretested data collection form. It was then transferred into the Spreadsheet of the Statistical Package for the Social Sciences (SPSS 24, IBM, Chicago, IL, USA). For quantitative variables, we estimated the median and its 25% quartile since the sample in subgroups was small. For qualitative variables, we presented the frequencies and percentage proportions. To associate the known risk factors to the successful outcomes at the last follow-up, we used nonparametric method and calculated two-sided Mann–Whitney (MW) P value. If it was <0.05, we considered it as statistically significant. The statistically significant variables were included in the binominal regression model using step out method to identify independent factors (predictors) linked to the success.

Results

Our cohort had 79 eyes of 79 patients with dislocated IOL. Their median age was 63.9 years (25% quartile 30; minimum 1.3 and maximum 90 years). Males were 49 (62%), and the right eyes were 42 (53.2%). The median interval between IOL dislocation and presentation at our institute was 1 month (25% quartile 0.2 months). In 20 (25.3%) eyes, the time interval between IOL implantation and IOL dislocation was <3 months. In the rest 59 eyes, IOL dislocation occurred 3 or more months after IOL implantation.

PEX (eight eyes) and other ocular comorbidities (eight eyes) were the main ocular comorbidities at presentation. In 18 eyes, there was a history of other ocular surgery in the past. In ten eyes, trauma was the underlying cause for IOL dislocation. The ocular details at presentation are given in Table 1. Nearly half of the participants had UCVA <20/400 at presentation.

Table 1

Profile of cases with dislocated intraocular lens managed at tertiary eye hospital of central Saudi Arabia

IOP at presentation
n	72
Median	17.5
25% quartile	14.2
Minimum	5
Maximum	38
Glaucoma
IOP ≤22 mmHg	60 (75.9)
IOP >22 mmHg	12 (15.2)
Missing	7 (8.9)
Signs
Ciliary injection	8 (10.1)
Cells in AC	27 (34.2)
Cells in PC	23 (29.1)
IOL in AC	16 (20.3)
IOL in PC	59 (74.7)
Posterior vitreous detachment	10 (12.7)
Vitreous hemorrhage	1 (1.3)
Retinal breaks	4 (5.1)
Retinal detachment	5 (6.3)
Type of cataract surgery in the past
None	6 (7.6)
Extracapsular surgery	27 (34.2)
Phacoemulsification	24 (30.4)
Scleral fixation	3 (3.8)
Others	4 (5.1)
Not available	15 (19.0)
IOL placement
In the posterior chamber	64 (81.0)
Scleral fixation	5 (6.3)
Missing	10 (12.7)
Type of IOL
Single-piece IOL	62 (78.5)
Multi-piece IOL	9 (11.4)
Missing	8 (10.1)
Time of IOL insertion
Primary IOL implant	57 (72.2)
Secondary IOL implant	8 (10.1)
Missing	14 (17.7)
Intra-operative complications
None	50 (63.3)
Yes	18 (22.8)

IOL: Intraocular lens, IOP: Intraocular pressure, AC: Anterior chamber, PC: Posterior chamber

Among 20 cases with dislocation within 3 months, posterior capsular defect (11), PEX (5), trauma (1), diabetes (10), and past ocular surgery (3) were noted. In contrast, late dislocation had trauma (10), past ocular surgery (18), and PEX (8) as the main risk factors. The possible causes of IOL dislocation in the group with dislocation within 3 months of the implant were compared to the group with dislocation after 3 months [Figure 1].

Figure 1

Causes of intraocular lens implant dislocation in the eyes with dislocation in 3 months of implant (a) and in the eyes with dislocation after 3 months and more of implantation (b)

Only one case was treated conservatively since dislocated lens was in the posterior chamber for 2 years, and there was total retinal detachment with extensive fibrosis. After controlling IOP and inflammation, rest of the eyes with dislocated IOL were surgically managed. The existing IOL was removed from 33 (41.8%) eyes. Newer IOL was scleral fixated in 18 (22.8%) eyes. In 5 (6.3%) eyes, IOL was repositioned. In 25 (31.6%) eyes, IOL was implanted at a later date as a secondary procedure.

Postoperative complications included; hypotony in 1 (1.3%) eye, increased IOP in 6 (7.6%) eyes, vitreous hemorrhage in 2 (2.6%) eyes, retinal breaks in 1 (1.3%) eye, retinal detachment in 2 (2.6%) eyes, corneal decompensation in 2 (2.6%) eyes, and malposition of IOL in 2 (2.6%) eyes.

The median duration of follow-up was 2.1 years (25% quartile 9 months minimum 1 month, maximum 9.5 years).

The anatomical success was achieved in 46 (58.2%) of eyes at the last follow-up. Of them, 19 (41.3%) eyes had repositioned IOL, 25 (54.3%) had secondary IOL implanted in eyes.

The UCVA before and at the last follow-up is compared in Figure 2. More than half of the eyes with dislocated IOL had functional normal vision after management. At the last follow-up, glaucoma: (5 eyes), epi-retinal membrane (2 eyes), retinal detachment (4 eyes), hypotony (1 eye), central macular edema (3 eyes), infection (1 eye), corneal decompensation (5 eyes), and amblyopia (1 eye) were the main causes of SVI.

Figure 2

Uncorrected visual acuity before and after the management of dislocated intraocular lens implant. X-axis shows grades of visual impairments. Y-axis shows the percentage of eyes with vision grade. Dark colored bar is the vision at presentation with dislocated intraocular lens. Light colored bars present vision grade at the last follow-up after the management of dislocated intraocular lens

The outcomes were associated with the known risk factors [Table 2]. Younger age (MW P = 0.02), longer gap between IOL implant and dislocation (MW P = 0.005), primary IOL implantation (MW P < 0.001), not having glaucoma at presentation (MW P = 0.02), IOL removal instead of repositioning and were positively associated to the better visual outcomes.

Table 2

Uncorrected visual acuity at the last follow-up in eyes managed for dislocated intraocular lens and its determinants

Quantitative variables	Vision 20/20-20/60 at last follow up (n=45)	Vision <20/60 at last follow up (P=34)	Validation (P)
Age
Median	60	68.6	MW 0.02
25% quartile	24	51.3
Duration of follow-up
Median	1.3	2.4	MW 0.2
25% quartile	0.6	1.7
The interval between IOL implant and dislocation (months)
Median	3	0.4	MW 0.005
25% quartile	0.5	0.02
Qualitative variables
Gender, n (%)
Male	29 (64.4)	20 (58.8)	0.6
Female	6 (35.6)	14 (41.2)
Trauma causing dislocation, n (%)
Yes	7 (15.6)	3 (8.8)	0.4
No	37 (82.2)	30 (88.2)
Missing	1 (2.2)	1 (2.9)
IOL type, n (%)
Single piece	1 (2.2)	4 (11.8)	0.12
Not-single piece	38 (84.4)	26 (76.5)
Missing	6 (13.3)	4 (11.8)
Intraoperative complication during cataract surgery, n (%)
Yes	7 (15.6)	11 (32.4)	0.1
No	31 (68.9	19 (55.9)
Missing	7 (15.6)	4 (11.8)
IOL insertion timing, n (%)
Primary IOL	33 (73.3)	4 (11.8)	<0.001
Secondary IOL	4 (8.9)	24 (70.6)
Missing	8 (17.8)	8 (23.5)
UCVA at presentation with dislocation, n (%)
20/20-20/200	27 (60.0)	24 (70.6)	0.09
<20/200	17 (37.8)	6 (17.6)
Missing	1 (2.2)	4 (11.8)
Glaucoma at presentation, n (%)
≤22 mmHg	38 (84.4)	22 (64.7)	0.02
>22 mmHg	3 (6.7)	9 (26.5)
Missing	4 (8.9)	3 (8.8)
PEX, n (%)
Yes	3 (6.7)	5 (14.3)	0.3
No	42 (93.3)	28 (80.0)
Missing	0 (0.0)	2 (5.7)
Trauma, n (%)
Yes	7 (15.6)	3 (14.3)	0.4
No	37 (82.2)	30 (80.0)
Missing	1 (2.2)	2 (5.7)
Type of IOL management, n (%)
Removed	24 (53.3)	9 (26.5)	0.06
Repositioned	8 (17.8)	10 (29.4)
None	13 (28.9)	15 (44.1)

IOL: Intraocular lens, IOP: Intraocular pressure, MW: Mann–Whitney, PEX: Pseudo exfoliation, UCVA: Uncorrected visual acuity

Regression analysis suggested that late IOL dislocation (P = 0.05) and “no glaucoma” (P = 0.05) were independent factors (predictor) for the successful outcome.

Discussion

The management of dislocated IOL has promising visual outcomes with more than half of the cases regaining “functional normal vision.” However, complications even after successful management justify their close monitoring for a long time. The time interval between the IOL implant and its dislocation and vision at presentation could help in predicting the success in vision gain after intervention.

Dislocation of IOL is uncommon. Its timing in relation to the cataract surgery could enable us to group them into early IOL dislocation (within 3 months) and late IOL dislocation (after 3 months).[10] In our study, the posterior capsular defect was main causes for the dislocation of IOL within 3 months. While trauma and other causes were responsible for IOL dislocation after 3 months of primary surgery. Previous researchers observed that the pathogenesis and causes differed in these two groups. In the IOL dislocation within 3 months, inadequate IOL fixation was the main underlying pathogenesis. Ascaso et al.[10] and Davis et al.[11] noted that changes in zonules and capsular bags due to trauma, PEX, uveitis, high myopia, and aging were the main factors related to late dislocation.

The largest series of dislocated IOL managed in Korea had 55% success rate to attain the functional normal vision.[8] This matched with the findings of our study. However, this was in contrast to the findings of Shingleton et al. who noted high success even in cases with PEX.[12] However, it should be noted that visual gain of 12 out of 81 eyes was excluded from the analysis as they had preexisting ocular comorbidities compromising the vision. Thus differential inclusion criteria could be the reason for these differential success rates.

Complications during the surgery and in the postoperative period to manage dislocated lens are a major challenge. In our study, the complication was in 15% of the eyes. Yang and Chao[13] noted glaucoma in 20% of cases and controlled IOP by medication. The risk of glaucoma and other complications was significantly less if dislocated IOL was managed through the pars plana instead of the anterior route.[14] Our cases were managed through the pars-plana route. This could be one reason for better visual outcomes and fewer complications, especially related to the cornea like endothelial decompensation.

Eyes with primary IOL in our study had good visual outcomes when managed through the pars-plana route. Al-Halafi et al.[15] also noted that management of dislocated IOL through the pars-plana route along with PPV if performed within 2 weeks of diagnosis, the visual outcomes were better.

RP is a known risk factor for dislocated IOL. Surprisingly, we did not have any case with this underlying etiology even though RP is the second leading cause of low vision disability in the Kingdom.[16] Scleral fixation of dislocated IOL in RP cases has shown promising outcomes and less complications.[17]

Longer interval between implantation and dislocation of IOL resulted in better visual outcomes in our study. Once the eye is stable following primary surgery, risk of macular changes, retinal detachment, and uncontrolled glaucoma affecting vision are less common.[1213] This could be the logic of having a better visual outcome in cases with a wider gap of dislocation following implantation.

High IOP at the time of managing dislocated IOL was a risk for less visual gain. In addition, at the last follow-up, SVI in our cohort was noted in five eyes with cystoid macular edema and hypotony. This suggests that lowering the IOP with medication before commencing surgery is vital.

Removal of dislocated IOL and perhaps inserting secondary IOL at a later stage seems to be a better option compared to the repositioning of dislocated IOL. In these cases, excessive intraocular manipulation could have caused structural damage to the eyes and poor vision.

We had only five cases with scleral fixated IOL among those presenting with IOL dislocation. Scleral fixated IOL has shown good visual outcomes by Cho and Yu[14] Scleral fixated IOL are more stable and are with fewer complications if implants are carried out through the pars-plana route. The status of zonules and the capsular bag seems to be better in our cohort as many had undergone IOL re-implant in the capsular bags.

There were a few limitations in our study. This being a retrospective study, the cohort was affected by the loss of data and improper documentation of many important risk factors. Association of such risk factors to management outcomes where a large number of missing data existed should be interpreted with great caution.

The management of dislocated IOL, although had promising visual outcomes, intra- and post-operative complication rates in our study was high. Close monitoring of such complex cases is needed to detect and manage complications. Glaucoma and early dislocation after cataract surgery could predict poor vision after dislocated IOL management. Hence, one should offer a guarded visual prognosis in such cases.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.