|SYMPOSIUM - DIABETIC RETINOPATHY UPDATE
|Year : 2014 | Volume
| Issue : 1 | Page : 55-61
Cataract surgery in diabetic patients
Department of Ophthalmology, Shrewsbury and Telford NHS Trust, Royal Shrewsbury Hospital, Shrewsbury, SY3 8XQ, United Kingdom
|Date of Web Publication||3-Mar-2015|
Royal Shrewsbury Hospital, Shrewsbury, SY3 8XQ
Source of Support: None, Conflict of Interest: None
Cataract is a common condition observed in patients with diabetes mellitus frequently requiring surgical intervention. Cataract surgery in diabetic patients may result in poor visual outcomes due to the progression of diabetic retinopathy and accelerated development of diabetic macular edema. Researchers and surgeons are interested in learning whether patients with diabetes have increased risks for complications from cataract surgery. In this review, I will evaluate the current management of the adverse events that may occur due to cataract surgery in diabetic patients.
Keywords: Cataract surgery, diabetic maculopathy, diabetic retinopathy
|How to cite this article:|
Hammam T. Cataract surgery in diabetic patients. Egypt Retina J 2014;2:55-61
| Introduction|| |
The prevalence of cataract increases with the duration of diabetes and is linked with the poor diabetic control. The average prevalence of cataract in young diabetics is 8%, while in older diabetics it is 25%. About 40% of patients for cataract surgery are diabetic of which 14% had retinopathy. ,,,
Cortical and posterior sub-capsular (PSC) cataracts are associated with diabetes; PSC changes are reported to be reflective of blood sugar level. 
Diabetic retinopathy (DR) may progress more after cataract surgery. Such progression may be observed in up to 20% of patients within 12 months of cataract surgery. 
The progression of retinopathy was noticed in 28% of eyes at 12 months after cataract surgery compared to 14% of the phakic eyes. In patients undergoing monocular surgery the difference was 36% for pseudophakic eyes versus 20% phakic eyes. 
Among patients who underwent cataract surgery at VAMCs throughout the US, those with ophthalmological manifestations of diabetes had a 33% increased risk for complications, compared with other patients.  Diabetic macular edema (DME) may worsen postoperatively; however, uncomplicated phacoemulsification surgery does not lead to accelerated DR. The preexisting ME, severity of DR and diabetic control are noted to increase the risk of progression of diabetic maculopathy. 
A study using Medicare claims data found that the risk for cataract-surgery complications was associated with the severity of the underlying DR. Patients with diabetes but no retinopathy and those with nonproliferative DR (NPDR) had no difference in the risk for complications, compared with nondiabetic patients. However, patients with preexisting proliferative DR had a 62% increased likelihood of severe complications. Two possible reasons for the increased postsurgical risk for complications include altered immunity that may predispose patients with diabetes to infection, and increased complexity of cataract surgery resulting from poor pupil dilation, bleeding, and other complications. 
| Methods|| |
A literature search on cataract surgery in diabetic patients, limited to English language over the last 10 years. Resources searched were Medline, EMBASE, UpToDate and the Cochrane library.
In this review article, I will discuss the management of the possible potential complications that can compromise the visual outcome after cataract surgery in diabetics.
| Possible Potential Adverse Events in Diabetics Which May Limit the Visual Outcomes After Cataract Surgery|| |
- Increased risk of postoperative cystoid macular edema (CME)
- Worsening of preexisting clinically significant ME
- Increased risk of posterior capsular opacification (PCO)
- Coexisting advanced diabetic eye disease
- Uncontrolled diabetes at the time of surgery may increase the risk of endophthalmitis.
| Use of Topical Nonsteroidal Antiinflammatory Drugs|| |
Nonsteroidal antiinflammatory drugs (NSAIDs) are now-a-days widely used in ophthalmology to reduce eye inflammation, pain, and CME associated with cataract surgery. Recently, new topical NSAIDs have been approved for topical ophthalmic use, allowing for greater drug penetration into the vitreous. Hence, new therapeutic effects can be achieved, such as a reduction of exudation secondary to diabetic maculopathy.
The role of topical nonsteroid antiinflammatory ophthalmic solutions as a prophylactic treatment against postoperative CME were was studied in two trials summarized in [Table 1].
|Table 1: The role of topical nonsteroid antiinflammatory ophthalmic solutions as a prophylactic treatment against postoperative CME|
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Nepafenac ophthalmic suspension
In a multicenter, randomized, double-masked, vehicle -controlled study Singh et al.  evaluated the role of nepafenac ophthalmic suspension 0.1% in preventing ME following cataract surgery in NPDR patients.
About 3.2% of patients in the nepafenac group developed ME versus 16.7% in the vehicle group (P < 0.001).
They concluded that nepafenac demonstrated statistically significant and clinically relevant advantages compared with vehicle in preventing ME and maintaining visual acuity (VA) in diabetic patients following cataract surgery.
Bromfenac sodium versus steroid
Endo et al.  compared the efficacy of bromfenac sodium ophthalmic solution (BF) and a steroidal solution when used prophylactically against CME and anterior-chamber inflammation after cataract surgery and to assess macular thickness changes using optical coherence tomography.
The anterior chamber flare was significantly lower in the BF group 2, 4, and 6 weeks postoperatively. The average perifoveal thickness values were significantly lower in the BF group at 4 and 6 weeks. No adverse events occurred in either group. They concluded that BF suppressed anterior chamber inflammation and increasing retinal thickening after cataract surgery in patients with NPDR.
| The Role of Advocating Antivascular Endothehal Growth Factor (Bevacizumab or Ranibizumab) at the Time of Cataract Surgery in Minimizing the Risk of Postoperative Cystoid Macular Edema|| |
Intravitreal anti-vascular endothehal growth factor (Anti-VEGF) agents have revolutionized the treatment of DME by demonstrating visual improvement in multiple randomized clinical trials. Intravitreal steroids have also shown efficacy in controlling DME and potentially in improving vision. 
Over the past few years, several prospective, randomized controlled trials (RCTs) have been published that advocated anti-VEGF at the time of cataract surgery to minimize the risk of postoperative maculopathy. These studies are summarized in [Table 2].
|Table 2: Use of intravitreal injection of anti-VEGF in diabetic patients undergoing cataract surgery|
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Six RCTs evaluated the role of advocating intravitreal VEGF at the time of cataract surgery to improve the visual outcome by minimizing the risk of ME. Five studies used bevacizumab and only one used ranibizumab.
Chae et al.  concluded in patients with stable DR without significant ME, intravitreal ranibizumab injection at the end of cataract surgery may prevent the postoperative worsening of ME and may improve the final visual outcome without affecting safety.
Similarly, Salehi et al.  evaluated the efficacy of intravitreal injection of bevacizumab at the time of cataract surgery on the postoperative progression of DR and diabetic maculopathy.
Progression of diabetic maculopathy occurred in 15 eyes (50%) in the control group and 2 eyes (7.4%) in the intervention group (P = 0.0008).
There was no statistically significant difference in postoperative VA between the 2 groups after 6 months (P = 0.5). Five eyes in the control group and 1 eye in the intervention group progressed to neo-vascular glaucoma. Difference in mean postoperative central macular thickness (CMT) was not statistically significant between both groups (P = 0.54).
They concluded that intravitreal administration of 1.25 mg bevacizumab at the time of cataract surgery was safe and effective in preventing the progression of DR and diabetic maculopathy.
Furthermore, Fard et al.  studied the role of intravitreal bevacizumab (IVB) injected at the time of cataract surgery on postoperative increase of retinal thickness (RT) in patients with DR.
One month after surgery, the control group showed a significant increase in CMT, whereas the bevacizumab group did not show an increase. After 6 months, there was no significant difference both in macular thickness and postoperative VA between the two groups.
They concluded intravitreal administration of 1.25 mg bevacizumab at the time of cataract surgery is effective just for the short-term and 6 months results are the same in both groups.
| Role of Intravitreal Bevacizumab Injection in Preventing Progression of Diabetic Retinopathy and Maculopathy in Patients Undergoing Cataract Surgery|| |
Lanzagorta-Aresti et al.  concluded IVB immediately after phacoemulsification prevents exacerbation of the ME seen in many diabetic patients with NPDR and ME. In addition, this effect seems to hold in the short-term.
Takamura et al.  studied the clinical effectiveness of IVB combined with cataract surgery for management of the postoperative increase of RT in patients with diabetic maculopathy.
They concluded short-term results suggest that IVB has the potential not only to prevent the increase in RT, but also reduce the RT of eyes with DME after cataract surgery. Further improvement of VA in bevacizumab-treated eyes may be dependent on a reduction in central RT.
Cheema et al.  evaluated the role of IVB injected at the time of cataract surgery on the progression of DR and diabetic maculopathy.
Progression of DR occurred in 15 eyes (45.45%) in the control group and 4 eyes (11.42%) in the intervention group (P = 0.002).
Progression of diabetic maculopathy occurred in 17 eyes (51.51%) in the control group and 2 eyes (5.71%) in the intervention group (P = 0.0001).
There was no statistically significant difference in postoperative VA between the 2 groups (P = 0.772). Two eyes in the control group and none in the intervention group progressed to neo-vascular glaucoma.
They concluded that intravitreal administration of 1.25 mg bevacizumab at the time of cataract surgery was safe and effective in preventing the progression of DR and diabetic maculopathy in patients with cataract and DR.
| The Role of Intravitreal Injection of Triamcinolone Acetonide on Macular Thickening|| |
Ahmadabadi et al.  assessed the effect of intraoperative intravitreal injection of triamcinolone acetonide (IVTA) on the CMT, visual outcomes, and development of CME after phacoemulsification in diabetic patients.
In this prospective randomized controlled study, patients with diabetes were randomly assigned to a treatment group, which received an IVTA at the end of phacoemulsification, and a control group, which had routine phacoemulsification.
There was no statistically significant difference between the two groups in the mean corrected distance VA at any follow-up examination (P > 0.05). The mean change in center-point thickness and central 1.0 mm subfield mean thickness was statistically significantly lower in the treatment group than in the control group at all follow-up visits (P < .05). Four eyes in the control group and no eye in the treatment group developed CME. Three eyes (15%) in the treatment group developed an intraocular pressure rise that was managed by topical medication.
They concluded intravitreal injection of triamcinolone reduced the amount of increase in center-point thickness and central 1.0 mm subfield mean thickness after phacoemulsification in eyes of diabetic patients. Although it also reduced the incidence of CME, it had no effect on VA gain.
Type of intraocular lens
Elgohary et al.  found that in diabetic patients, hydrophobic acrylic intraocular lens (IOLs) can lead to an increased flare in the early postoperative period, but they seem to be more favorable than plate-haptic silicone IOLs because the latter lead to more PCO.
There was no significant difference in VA or contrast sensitivity at any postoperative visit between the two types of IOLs.
They concluded that the use of hydrophobic acrylic IOLs with square edge design can reduce the risk of posterior capsular thickening.
Triamcinolone-induced cataract in eyes with DME
Prospective data from a randomized clinical trial Gillies et al.,  described the 3 years risk of cataract after intravitreal triamcinolone (IVTA) injections for DME and the outcomes of cataract surgery.
At baseline, 27 phakic eyes with DME were randomized to receive IVTA and 25 to receive sham injection. After 2 years, initial sham-treated eyes were eligible to receive IVTA as the study became open label for the 3 rd year. The cumulative incidence of cataract surgery was the primary outcome of the study. Other outcomes assessed included progression of cataract, best-corrected logarithm of the minimal angle of resolution VA before and after surgery and CMT.
Over the 3 years of the study, 15/27 (56%) phakic eyes in the IVTA treated group underwent cataract surgery when compared with 2/25 (8%) initial sham-treated eyes (P < 0.001). Mean VA 6 months after cataract surgery was better than at entry into the trial. Two (15%) of the eyes in the IVTA-treated group undergoing cataract surgery had a loss of >15 letters.
In the IVTA-treated group, 10/15 (67%) eyes that had three or more injections had progression of PSC cataract by >2 grades when compared with only 2/12 (17%) eyes that had fewer than three injections (P = 0.009).
They concluded over half of the eyes receiving IVTA injections for DME required cataract surgery within 3 years. In eyes with three or more IVTA injections, two-thirds had progression of PSC cataract. Visual outcomes after cataract surgery were generally good, although a small proportion of eyes lost >15 letters over the course of study.
| Corneal Changes During Cataract Surgery|| |
In randomized comparative controlled trial Altintas et al.  studied the corneal thickness changes caused by phacoemulsification times in diabetic and nondiabetic patients. Corneal thicknesses were greater in the first postoperative week both in diabetic and nondiabetic patients than in later follow-up. Later corneal thicknesses were not different according to phaco-times or diabetic status. In terms of corneal thickness changes, uncomplicated phacoemulsification is safe in diabetics and nondiabetics.
| Coexisting Proliferative Diabetic Eye Disease Requiring Panretinal Photocoagulation|| |
Suto et al.  studied fifty eight eyes of 29 patients with similar bilateral cataracts and severe nonproliferative or early proliferative DR were randomly assigned for treatment with cataract surgery performed after panretinal photocoagulation (PRP-first group) or before PRP (surgery-first group). Treatment was performed in the opposite order in the contralateral eye.
The main outcome measure was best corrected VA (BCVA) 12 months after surgery.
The secondary outcome measures were the laser parameters, progression of retinopathy and ME, and aqueous flare intensity.
The percentage of eyes with a BCVA of 20/40 or better was statistically significantly higher in the surgery-first group (96.6%) than in the PRP-first group (69.0%) (P = 0.012).
The rate of the progression of ME was significantly decreased in the surgery-first group (P = 0.033). There was no significant difference between the two groups in the other outcome measures.
They concluded although the order in which PRP and cataract surgery were performed had no effect on postoperative retinopathy, the BCVA was better and the rate of the progression of ME was decreased in the surgery-first group.
| Endophthalmitis|| |
Patients with diabetes mellitus (DM) are known to have an impaired immune response and may be at a higher risk for developing postoperative infections. Effectively at the cellular and humoral levels, there is suboptimal response to different antigens in addition to altered phagocytic capabilities. ,,,
Two reports showed that approximately 14-21% of postoperative patients who develop endophthalmitis are diabetic. , In addition, the microorganisms that grew from eyes of diabetic subjects had a preponderance of more virulent organisms at 26% versus 22% isolated from eyes in nondiabetic patients. 
Raised levels of glucose in the skin, mucous membranes and the tear film of patients with DM, microorganisms growth seems definitely promptly. Postoperative endophthalmitis is most often associated with Gram-positive organisms (75-80%), next in frequency are Gram-negative organisms (15-29%), and least often fungi (3-13%). When cultures were obtained from nondiabetic patients they were likely to show no growth in as many as twice the number noted in cultures from diabetic subjects that is at 33% versus 15%, respectively.
In addition, the microorganisms that grew from eyes of diabetic subjects had a preponderance of more virulent organisms at 26% versus 22% isolated from eyes in nondiabetic patients. 
The most common organism isolated from diabetic patients with acute endophthalmitis is coagulase-negative staphylococci.  In another study, both Types 1 and 2 diabetic patients grew Staphylococcus epidermis and Staphylococcus aureus at 11.79% and 11.7%, respectively for Type 1, and 24.2% and 21.2% for Type 2.  There was a trend for a higher preponderance of coagulase-negative staphylococcal isolates in patients who had preexisting DR.  Phillips and Tasman found a higher prevalence of Gram-negative isolates of Staphylococcus organisms among their patients. Remarkably none of their patients had Gram-negative endophthalmitis.  Of note, is the conjunctival flora of diabetic subjects differed from that isolated from nondiabetic subjects. 
| Conclusion|| |
Patients with no retinopathy or with background DR with no maculopathy do not require any special measure if their cataract procedure was uncomplicated.
On the other hand, patients with previously treated ME or with ME at the time of the cataract surgery will benefit from intravitreal anti-VEGF at the conclusion of their cataract surgery.
Patients with proliferative DR at the time of cataract surgery, the laser treatment can be done prior to the cataract procedure if the view allowed that. However, if the view is hazy, PRP using binocular indirect ophthalmoscope can be started at the end of phaco-emulsification and IOL. I usually insert a single figure of eight 10/0 nylon to avoid any wound hydration and iris prolapse during the laser treatment.
Patients with high blood glucose level at the time of their procedure should be cancelled and referred back to their diabetologist for better control. There is no published guideline regarding the cut-off limit where the patients should be cancelled. In my practice patients with BM of 18 mmol/ul or higher are cancelled.
Treating any preexisting ocular surface infection, wound construction, minimal tissue trauma and meticulous clean of the cortical lens fibers will help in avoiding surgical complications.
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[Table 1], [Table 2]