Glistenings are fluid-filled microvacuoles that can result from water condensation within the intraocular lens (IOL) optic.1 Most available studies on glistening are associated with hydrophobic acrylic IOLs. The packaging environment and temperature changes have been proposed as factors that promote water condensation within the IOL optic.2–6 The visual significance of glistenings is still controversial, but there is suspicion that severe glistenings may affect visual function, including decreases in contrast sensitivity and visual acuity.1,7
The enVista MX60 (Bausch & Lomb, Rochester, NY) is a new-generation hydrophobic IOL. Following a multicenter, prospective, randomized clinical trial,8 the en-Vista MX60 was approved by the U.S. Food and Drug Administration as a single-piece hydrophobic acrylic IOL in 2012. The enVista MX60 IOL optic and haptics are lathed and milled from a single button made from a proprietary soft hydrophobic acrylic polymer, which incorporates an ultraviolet-absorbing chromophore.9 To ensure that the IOL remains free of glistening, it is prehydrated to equilibrate the water content.
We report the first case of IOL glistening 6 months after microincision phacoemulsification and in-the-bag implantation of an enVista MX60 IOL in a patient with uncontrolled diabetes mellitus.
A 76-year-old woman with corticonuclear cataract (grade III in the Lens Opacities Classification System III) underwent uneventful cataract surgery by 2.2-mm microincision phacoemulsification and in-the-bag implantation of an enVista MX60 IOL in the right eye. After 3 months, uneventful cataract surgery and implantation of an Akreos Adapt AO IOL (Bausch & Lomb) were performed in the left eye.
The patient had a 14-year history of non-insulin–dependent (type II) diabetes mellitus and was taking oral hypoglycemic agents, but her blood sugar was poorly controlled. Fasting blood glucose level was 73 mg/dL, postprandial 2-hour glucose level was 274 mg/dL, and hemoglobin A1C level was 7.5%. Preoperative fundus examination revealed epiretinal membrane on the left eye, which was confirmed by optical coherence tomography, and diabetic retinopathy in both eyes. Before surgery, the corrected distance visual acuity (CDVA) was 0.06 (20/320 Snellen) in the right eye and 0.4 (20/50 Snellen) in the left eye. Uneventful phacoemulsification through a 2.2-mm clear corneal incision using the phaco-chop technique with IOL implantation (enVista MX60, +22.0 diopters, serial number 3351114013) in the right eye was performed on November 27, 2013.
At the 1-week postoperative visit, slit-lamp examination revealed no significant ocular inflammation and perfect IOL positioning in the posterior chamber. The CDVA improved to 0.8 (20/25 Snellen) at 1 month postoperatively. Panretinal photocoagulation for diabetic retinopathy was performed in the left eye before cataract surgery (Figure 1). After performing phacoemulsification and IOL implantation in the left eye, the CDVA was 0.4 (20/50 Snellen) at 1 month due to an epiretinal membrane on the left eye. Pars plana vitrectomy for epiretinal membrane treatment was discussed with the patient. At 6 months, a glistening formation within the IOL optic was observed under slit-lamp examination in the right eye (Figure 2). The pattern appeared different from the one the authors had seen before; diffuse whitish grade 1 glistenings with small, round clear zones in a regular manner were observed on the entire optic. Although no glistening was detected on the left eye, there was mild posterior capsular opacity. The CDVA was the same as at the previous follow-up visit, 0.8 (20/25 Snellen) in the right eye and 0.4 (20/50 Snellen) in the left eye.
Fundus photographs showing multiple dot and blot hemorrhages in both eyes (A = right eye; B = left eye). Panretinal photocoagulation for diabetic retinopathy was performed in the left eye.
Slit-lamp photograph of the right eye with an enVista MX60 intraocular lens (Bausch & Lomb, Rochester, NY). Diffuse whitish glistening formations (arrows) are visible on the optic of the intraocular lens with small, round clear zones (arrowheads) in a regular manner.
During follow-up, the patient continued to have poorly controlled diabetes mellitus; fasting blood glucose level was 154 mg/dL, postprandial 2-hour glucose level was 256 mg/dL, and hemoglobin A1C level was 7.8%. IOL explantation or exchange was not taken into consideration at this time point due to better visual acuity compared to the fellow eye and no complaints in the right eye.
To the best of our knowledge, no cases of glistening after implantation of the enVista MX60 IOL have been reported. The enVista MX60 IOL itself is packaged in physiologic saline to eliminate fluid exchange with the aqueous humor. Prehydration of the enVista MX60 IOL to equilibrate the water content was designed to maintain the IOL glistening-free.9 Another characteristic of the enVista MX60 IOL is its rigid optic material. The material from which the enVista MX60 lens is manufactured has a relatively high glass transition temperature (28°C), which results in slow unfolding in the eye. To shorten the unfolding time of the enVista MX60 IOL, we used a 30°C ophthalmic viscosurgical device immersed in 36°C normal saline for less than 60 seconds.10 In a previous study,10 this indirect IOL warming method did not exceed the average aqueous humor temperature (34.0°C to 35.5°C). Thus, this warm ophthalmic viscosurgical device does not seem to affect the glistening formation observed in this patient. This was the only case to develop IOL glistening among 137 eyes with an enVista MX60 IOL implanted using this indirect IOL warming in our institution over 2 years.
Glistening results from the accumulation of water or aqueous humor inflow into the IOL optic, but the exact pathophysiology remains unclear.2,3 The pattern of glistenings observed in the case described in this report had small, round clear zones in a regular manner between diffuse glistenings. Glistenings with round clear zones appeared to be relatively on the surface of the optic. Based on the pattern and layer of glistenings in this case, this might seem to be produced due to the IOL surface treatment, manufacturing, or packaging process.
High blood glucose in diabetic patients results in edema of the iris capillary endothelium, which leads to a decrease in the resistance of the vessel wall and an increase in blood–aqueous barrier permeability. Although the exact relationship between poor glycemic control in diabetes mellitus and IOL glistening is not completely understood, poor glycemic control may theoretically be a risk factor for IOL glistening through disruption of the blood–aqueous barrier.
This case shows that glistening can develop in certain situations within the enVista MX60 IOL. This finding strongly suggests that increased hemoglobin A1C level might be one of the risk factors for glistening formation, even with a prehydrated hydrophobic IOL. Tight glycemic control should be emphasized to avoid this complication even after uneventful surgeries.
- Dhaliwal DK, Mamalis N, Olson RJ, et al. Visual significance of glistenings seen in the AcrySof intraocular lens. J Cataract Refract Surg. 1996;22:452–457. doi:10.1016/S0886-3350(96)80041-1 [CrossRef]
- Gregori NZ, Spencer TS, Mamalis N, Olson RJ. In vitro comparison of glistening formation among hydrophobic acrylic intraocular lenses. J Cataract Refract Surg. 2002;28:1262–1268. doi:10.1016/S0886-3350(02)01224-5 [CrossRef]
- Miyata A, Yaguchi S. Equilibrium water content and glistenings in acrylic intraocular lenses. J Cataract Refract Surg. 2004;30:1768–1772. doi:10.1016/j.jcrs.2003.12.038 [CrossRef]
- Ayaki M, Nishihara H, Yaguchi S, Koide R. Surfactant induced glistening: surface active ingredients in ophthalmic solutions may enhance water entry into the voids of implanted acrylic intraocular lenses. J Long Term Eff Med Implants. 2006;16:451–457. doi:10.1615/JLongTermEffMedImplants.v16.i6.50 [CrossRef]
- Kato K, Nishida M, Yamane H, Nakamae K, Tagami Y, Tetsumoto K. Glistening formation in an AcrySof lens initiated by spinodal decomposition of the polymer network by temperature change. J Cataract Refract Surg. 2001;27:1493–1498. doi:10.1016/S0886-3350(01)00895-1 [CrossRef]
- Oshika T, Shiokawa Y, Amano S, Mitomo K. Influence of glistenings on the optical quality of acrylic foldable intraocular lens. Br J Ophthalmol. 2001;85:1034–1037. doi:10.1136/bjo.85.9.1034 [CrossRef]
- Gunenc U, Oner FH, Tongal S, Ferliel M. Effects on visual function of glistenings and folding marks in AcrySof intraocular lenses. J Cataract Refract Surg. 2001;27:1611–1614. doi:10.1016/S0886-3350(01)00995-6 [CrossRef]
- Packer M, Fry L, Lavery KT, et al. Safety and effectiveness of a glistening-free single-piece hydrophobic acrylic intraocular lens (enVista). Clin Ophthalmol. 2013;7:1905–1912. doi:10.2147/OPTH.S50499 [CrossRef]
- Heiner P, Ligabue E, Fan A, Lam D. Safety and effectiveness of a single-piece hydrophobic acrylic intraocular lens (enVista®): results of a European and Asian-Pacific study. Clin Ophthalmol. 2014;8:629–635. doi:10.2147/OPTH.S56135 [CrossRef]
- Eom Y, Lee JS, Rhim JW, Kang SY, Song JS, Kim HM. A simple method to shorten the unfolding time of prehydrated hydrophobic intraocular lens. Can J Ophthalmol. 2014;49:382–387. doi:10.1016/j.jcjo.2014.06.002 [CrossRef]