Partial characterization of a putative new growth factor present in pathological human vitreous

Incidence and Risk of Scleral-Fixated Akreos (AO60) Lens Opacification: A Case Series

Purpose:

Postoperative hydrophilic intraocular lens opacification can lead to decreased vision and may require intraocular lens exchange. This study aims to identify the incidence of scleral-fixated Akreos AO60’s (Bausch + Lomb) lens opacification and risk factors for this phenomenon.

Methods:

This is a retrospective case series of all patients who underwent scleral-fixated Akreos AO60 lens at our institution between January 1, 2015 and December 31, 2019. The following data were recorded: age, sex, medical history, indication for Akreos AO60 implantation, laterality, ocular history, previous ocular surgical procedures, subsequent intraocular surgical procedures after the Akreos implantation, lens opacification, visual significance of opacification, and Akreos explantation. Intraoperative and postoperative complications were recorded. Main outcome measures were the overall incidence of Akreos lens opacification as well as the incidence of these eyes undergoing subsequent intraocular surgery.

Results:

A total of 262 eyes of 257 patients underwent Akreos lens implantation. Overall, 2% (5 of 262) developed lens opacification. Two patients had Descemet stripping automated endothelial keratoplasty (DSAEK) concurrently with Akreos implantation. One patient underwent subsequent Baerveldt glaucoma implantation and DSAEK. The fourth patient had vitrectomy with sulfur hexafluoride gas followed by DSAEK. This represents a 25% (4 of 16) opacification rate among all patients who underwent DSAEK ( P ≤ .01, Fisher exact test). One patient developed opacification after undergoing 2 vitrectomies for retinal detachment in the absence of DSAEK.

Conclusions:

Akreos lens opacification can be visually significant and may occur after a retinal or corneal procedure that involves the use of intraocular gas or air.

Human vitreous in proliferative diabetic retinopathy: Characterization and translational implications

Diabetic retinopathy (DR) is one of the leading causes of visual impairment in the working-age population. DR is a progressive eye disease caused by long-term accumulation of hyperglycaemia-mediated pathological alterations in the retina of diabetic patients. DR begins with asymptomatic retinal abnormalities and may progress to advanced-stage proliferative diabetic retinopathy (PDR), characterized by neovascularization or preretinal/vitreous haemorrhages. The vitreous, a transparent gel that fills the posterior cavity of the eye, plays a vital role in maintaining ocular function. Structural and molecular alterations of the vitreous, observed during DR progression, are consequences of metabolic and functional modifications of the retinal tissue. Thus, vitreal alterations reflect the pathological events occurring at the vitreoretinal interface. These events are caused by hypoxic, oxidative, inflammatory, neurodegenerative, and leukostatic conditions that occur during diabetes. Conversely, PDR vitreous can exert pathological effects on the diabetic retina, resulting in activation of a vicious cycle that contributes to disease progression. In this review, we recapitulate the major pathological features of DR/PDR, and focus on the structural and molecular changes that characterize the vitreal structure and composition during DR and progression to PDR. In PDR, vitreous represents a reservoir of pathological signalling molecules. Therefore, in this review we discuss how studying the biological activity of the vitreous in different in vitro, ex vivo, and in vivo experimental models can provide insights into the pathogenesis of PDR. In addition, the vitreous from PDR patients can represent a novel tool to obtain preclinical experimental evidences for the development and characterization of new therapeutic drug candidates for PDR therapy.

Opacification of the optic of an Akreos Adapt intraocular lens

A 60-year-old diabetic patient transferred to our retina clinic for a regular follow-up for diabetic retinopathy. He had uneventful cataract surgery at the time of pars plana vitrectomy in the right eye due to diabetic retinopathy at a private ophthalmologic hospital. Six months after the surgery, neovascular glaucoma with hyphema developed in the right eye and an Ahmed valve was implanted at our hospital. Ten months after cataract surgery, we found opacification of the intraocular lens (IOL) which was causing significant visual disturbance. At the time, the best corrected visual acuity (BCVA) in the right eye was hand motion. The IOL was explanted 45 months after the operation. Five months after explantation, the BCVA was 0.06. Unfortunately, pathologic analysis was not performed. Patient-related factors such as an anterior chamber reaction caused by hyphema might have been responsible for the opacification. To our knowledge, there are no previous reports of opacification of the Akreos Adapt IOL.

Surface calcification of hydrophilic acrylic intraocular lens related to inflammatory membrane formation after combined vitrectomy and cataract surgery

Two patients complained of blurred vision approximately 6 months after having combined vitrectomy and phacoemulsification with implantation of a C-flex 570C hydrophilic acrylic intraocular lens (IOL). Multiple granules were noted on the anterior surface of the IOLs in both patients. Intraocular lens exchange was performed in both eyes, and the explanted IOLs were sent for histopathological analysis. Scanning electron microscopy confirmed the presence of cracks and granules on the IOL surfaces and energy-dispersive x-ray spectroscopy demonstrated calcium deposition. Based on the calcification pattern on the anterior surface of the IOLs, 2 additional cases of opacification were identified under slitlamp examination.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Analysis of aqueous humor calcium and phosphate from cataract eyes with and without diabetes mellitus

Purpose

To compare the levels of calcium and phosphorus in the aqueous humor and serum of diabetics and non-diabetics.

Methods

We divided patients into two groups: seventy-six non-diabetic cataract patients and fifty-two diabetic cataract patients. The diabetic group was divided again into three subgroups: twenty-six patients with no diabetic retinopathy, thirteen patients with non-proliferative diabetic retinopathy, and thirteen patients with proliferative diabetic retinopathy. The authors compared the levels of calcium and phosphorus in the serum and aqueous humor of cataract patients. Statistic analysis was performed to form two comparisons: 1) a comparison between non-diabetics and diabetics and 2) a comparison among non-diabetics and the three subgroups of diabetics.

Results

In serum, calcium levels did not statistically differ between non-diabetics and diabetics. The phosphorus level was also not significantly different. In the aqueous humor, however, while calcium levels did not differ significantly, the phosphorus levels in diabetics were considerably higher than those in non-diabetics. When non-diabetics were compared to the three diabetic subgroups, calcium levels did not differ in serum or aqueous humor, but the phosphorus levels in diabetics with proliferative diabetic retinopathy were significantly higher than those in non-diabetics, diabetics without diabetic retinopathy, and diabetics with non-proliferative diabetic retinopathy.

Conclusions

The level of phosphorus in the aqueous humor and serum of diabetics was significantly increased, especially in diabetics with proliferative diabetic retinopathy. This result may be related to hydrophilic acrylic IOL opacification. Future studies regarding the pathogenic role of a high concentration of aqueous humor and serum phosphorus are required.

Diabetes can alter the signal transduction pathways in the lens of rats

Diabetes is known to affect cataract formation by means of osmotic stress induced by activated aldose reductase in the sorbitol pathway. In addition, alterations in the bioavailability of numerous extralenticular growth factors has been reported and shown to result in various consequences. We have found that the basic fibroblast growth factor (bFGF) accumulates in the vitreous humor of 3- and 8-week diabetic rats. Consequently, the associating signal transduction cascades were severely disrupted, including upregulated phosphorylation of extracellular signal-regulated kinase (ERK) and the common stress-associated mitogen-activated protein kinases p38 and SAPK/JNK. Conversely, under diabetic condition, we observed a dramatic inhibition of phosphatidylinositol-3 kinase activity in lenses obtained from the same animal. Rats treated with the aldose reductase inhibitor AL01576 for the duration of the diabetic condition showed that the diabetes-induced lenticular signaling alterations were normalized, comparable to controls. However, treatment of AL01576 in vitro was ineffective at normalizing the altered constituents in extracted diabetic vitreous after the onset of diabetes. The effect of AL01576 in the high galactose-induced cataract model in vitro was also examined. Administration of AL01576 to lens organ culture normalized the aberrant signaling effects and morphological characteristics associated with in vitro sugar cataract formation. In conclusion, our findings demonstrate diabetes-associated alterations in the lens signal transduction parameters and the effectiveness of AL01576 at normalizing such alterations. The causes for these alterations can be attributed to elevated vitreal bFGF in conjunction with osmotic stress and associated attenuation in redox status of the lens.

Inositol 1,4,5-Trisphosphate-independent Ca2+Mobilization Triggered by a Lipid Factor Isolated from Vitreous Body

A complex phospholipid from bovine vitreous body with a strong Ca(2+)-mobilizing activity has been recently isolated to homogeneity by our group. In this work, a sequential analysis of its transmembrane signaling pathway has been undertaken to characterize the intracellular mechanisms responsible for the Ca(2+) rise. The results show that this phospholipid induces, in a dose-dependent manner (ED(50) of around 0.25 microgram/ml), a Ca(2+) mobilization from inositol 1,4,5-trisphosphate-insensitive intracellular stores, with no participation of extracellular Ca(2+). Upon repeated administration, it shows no signs of autologous desensitization, does not induce heterologous desensitization of the L-alpha-lysophosphatidic acid (LPA) receptor but is desensitized by the previous administration of LPA. The Ca(2+)-mobilizing activity requires a membrane protein, is blocked after preincubation of the cells with pertussis toxin and phorbol esters, as well as by U73122 (an inhibitor of phospholipases C/D), R59022 (a diacylglycerol kinase inhibitor), and D609 (which inhibits phosphatidylcholine-specific phospholipase C). Upon administration of this phospholipid, the intracellular levels of phosphatidic acid (PA) rise with a time course that parallels that of the Ca(2+) mobilization, suggesting that PA could be responsible for this Ca(2+) signal. Exposure to AACOCF(3) (a specific inhibitor of phospholipase A(2)) does not modify the Ca(2+) rise, ruling out the possibility that the PA generated could be further converted to LPA by the action of phospholipase A(2). Based on the experimental data obtained, a signaling pathway involving a phosphatidylcholine-specific phospholipase C coupled to diacylglycerol kinase is proposed. This compound may represent a new class of bioactive lipids with a putative role in the physiology of the vitreous body.

Angiotensin II receptor subtype gene expression and cellular localization in the retina and non-neuronal ocular tissues of the rat

In addition to its function as a peripheral hormone, angiotensin II (AngII) has been shown to act as a neuromodulator in various brain regions. AngII effects are mediated by two major AngII receptor subtypes, AT1 and AT2, and different AT1 receptor isoforms AT1A and AT1B are described in rat brains. The purpose of the present study was to analyse the expression pattern of AT receptors in different parts of the rat eye with special emphasis on the retina. Specific primers were constructed and the gene expression of AngII receptor subtypes was investigated by means of reverse transcription-polymerase chain reaction (RT-PCR). An antibody was used for cellular localization of AT1 receptor in the retina. AT2 receptor mRNA was localized by in situ hybridization (ISH). We examined the retinas of different developmental stages as well as non-neuronal ocular tissues, e.g. choroid and anterior uveal tract of rats (Brown Norway and Wistar strain), for the gene expression of AT receptors. Our results show that AT1A and AT2 mRNAs are expressed in rat choroid, iris/ciliary body and retinas, whereas AT1B mRNA is not expressed in the retina but in all other ocular tissues under investigation. AT1 receptor immunohistochemistry of the retina showed strong labelling in the ganglion cell layer (GCL), and some cells in the inner nuclear layer (INL), suggesting putative ganglion cell but also amacrine cell labelling. In the retina, ISH for AT2 mRNA revealed labelling in the GCL and a faint labelling in the inner nuclear layer. No AT2 ISH-signal was found in the other ocular tissues. These data suggest that there is a specific distribution pattern of AT receptors in rat ocular tissues, especially in the retina. The expression of AT receptors on retinal ganglion cells confirms the AngII action on these cell types and supports the role of AngII as a retinal neurotransmitter or neuromodulator.

Isolation of a bioactive Ca(2+)-mobilizing complex lipid from bovine vitreous body

Vitreous body extracts show a potent Ca(2+)-mobilizing activity on fibroblast cells. This Ca2+ signal is complex, and due to the presence of two different bioactive substances. The first one was identified as acid FGF. The second one was shown to be a low molecular weight substance identified as a complex lipid by a combination of chromatographic and biochemical data. This finding raises the possibility that non-classical substances with growth factor-like activity might play a role in the regulation of proliferative processes in the eye.