Reviews for the Softec Hd Oval Lens for Dysphotopsias

• Journal List
• Clin Ophthalmol
• v.5; 2011
• PMC3033005

Clin Ophthalmol. 2011; 5: 65–seventy.

Softec Hard disk hydrophilic acrylic intraocular lens: biocompatibility and precision

Ladan Espandar

¹ Section of Ophthalmology, Tulane University, New Orleans, LA, USA

Shameema Sikder

² Wilmer Eye Establish, Johns Hopkins Academy, Baltimore, Physician, U.s.

Majid Moshirfar

ⁱⁱⁱ John A Moran Centre Center, University of Utah, Salt Lake Urban center, UT, USA

Abstract

Intraocular lens development is driven past higher patient expectations for ideal visual outcomes. The recently US Food and Drug Administration-approved Softec Hard disk drive^™ lens is an aspheric, hydrophilic acrylic intraocular lens (IOL). The hydrophilic design of the lens is optimized to address dysphotopsia while maintaining biocompatibility, optical clarity, resistance to harm, and resistance to biocontamination. Aspheric lenses decrease postoperative spherical aberration. The addition of the Softec lens provides clinicians with some other selection for IOL placement; however, randomized comparative studies of this lens to others already on the market remain to be completed.

Keywords: hydrophilic acrylic intraocular lens, Softec Hard disk intraocular lens, aspheric intraocular lens, IOL

Overview

The Softec Hard disk drive^™ posterior chamber intraocular lens (Lenstec Inc., Leningrad, FL, USA) is an ultraviolet (UV)-arresting, unmarried-piece modified "C" loop intraocular lens (IOL) with a symmetrical anterior and posterior surface aspheric design (zero aberration) (Figure one). The Lenstec Softec Hard disk IOL is manufactured completely from a medical-grade copolymer of hydrophilic acrylic hydroxyethylmethacrylate (HEMA, 26% water content) and a polymerizable UV blocker. The overall length of the lens is 12.0 mm. The 5.v-mm-long lens optic has a 360° square border blueprint, designed for placement in the capsular bag. This lens is offered in power options in 0.25-D steps across the +18 to +25 D range, allowing more than precise power correction.¹

Softec HD lens (image provided by Lenstec Inc., Leningrad, FL, United states of america).

Although the Softec HD intraocular lens has been implanted in Europe since 2005, it was canonical by the United states of america Food and Drug Administration (FDA) in Apr 2010. This written report summarizes the available information on the key characteristics of Softec HD IOLs, including biocompatibility, precision, optical clarity, and stability.

Advantages of hydrophilic acrylic fabric

Despite a decade of popularity elsewhere, hydrophilic acrylic IOLs have not gained popularity in the US due to several early on reports of calcification and opacification.^{two – 9} Recently, a new generation of hydrophilic acrylic IOLs has been approved past the FDA and is now available for clinical use in the US.

Hydrophilic acrylics offering concrete, biological, and optical qualities that make them suitable for use in foldable IOLs. These characteristics include the following:

1. Less dysphotopsia: Hydrophilic acrylic IOLs take college h2o content and therefore a decreased refractive alphabetize relative to hydrophobic IOLs, minimizing bug with glare, external and internal reflections, and other unwanted visual phenomena.^{10 – 12}

2. Practiced biocompatibility: Khan and Percival¹³ followed patients with hydrophilic IOLs for 12 years and reported good flexibility and biocompatibility with minimal inflammatory reaction in the eye. These IOLs have less effect on the blood–aqueous bulwark and may exist a meliorate pick for uveitic and diabetic patients.

3. Good optical clarity: Despite the early reports of calcification in a few types of hydrophilic IOLs,¹⁴ new hydrophilic IOLs take different copolymer limerick,ⁱ and there have not been whatever reports of calcification or glistening in the last v years.

4. Resistance to damage during insertion: Hydrophilic acrylic IOLs resist fold marks and forcep harm in contrast to silicone or hydrophobic IOLs.

5. Less susceptibility to biocontamination: Schauersberger et al^xv exposed nine different types of IOLs to standardized suspensions of Staphylococcus epidermidis for 5 minutes, and so rinsed and tested them for the presence of bacteria. Poly(methyl methacrylate) and hydrophobic IOLs had bacterial densities two or more than times higher than hydrophilic IOLs. Schauersberger et al^xv concluded that hydrophilicity of IOL material was inversely related to adhesion and bacterial density on the IOL surface.

Advantages of zero aberration aspherical IOLs

Several studies^{16 – 19} have shown that aspheric IOLs tin can provide patients with significant optical benefits over traditional spherical surface IOLs. These optical benefits are due to a reduction in optical aberrations, particularly spherical aberration at the retina. The mean corneal spherical aberration is about +0.27 microns²⁰ (90% of the population have positive corneal spherical aberration, whereas 10% have negative corneal spherical aberration).²¹

A arched IOL with spherical surfaces exhibits positive spherical aberration. Thus, usually, spherical IOLs add together positive spherical abnormality to the already positive corneal spherical aberration. Aspheric IOLs attempt to improve pseudophakic vision past controlling spherical aberrations. 1 strategy is to design a lens with negative spherical aberrations to residuum the normally positive corneal spherical aberrations. Some other strategy is to blueprint a lens with minimum spherical aberrations (symmetric versus asymmetric conic surface) then that no additional spherical abnormality is added to the corneal spherical aberrations.

Dr Sarver²² used a Kooijman²⁰ center model to compare the performance of different aspheric and spheric blueprint IOLs in different settings, including lens decentration, lens tilt, and photopic and scotopic conditions. In this model, when the lens was centered, the spherical IOL performed worst and the negative spherical aberration IOL performed all-time. In cases of ane.0 mm decentration, the spherical surface and negative spherical aberration IOLs did not perform as well as nix aberration IOL designs, even when the trends for decentration did not depend on educatee size or corneal eccentricity. When considering tilting of the IOL, the performance of the IOL designs were comparable in most cases. The nothing spherical aberration IOLs outperformed the spherical surface and negative spherical abnormality IOLs.

In cases of 0.5 D of defocus at 3.0 and v.0 mm pupils, the performances of all IOLs were about equal. The negative spherical abnormality IOL showed more contrast for low-frequency objects than the other IOLs did. The negative spherical aberration IOL showed pregnant regions of contrast reversal at 5.0 mm pupils. The equal conic IOL and unequal conic IOL designs appeared to perform about the aforementioned.

There are specific conditions in which one IOL design volition perform ameliorate than some other, but, generally, aspheric IOLs perform better than spherical surface IOLs. For the level of alignment errors, zero spherical aberration IOLs perform better than spherical surface IOLs and negative spherical abnormality IOLs. The equal and unequal conic IOL designs perform similarly. The equal conic IOL design performs slightly improve than the unequal conic IOL design in terms of smaller variability in tangential and sagital modulation transfer function (MTF) components in dissimilar settings, including decentration and tilt.²⁴

Advantages of 0.25 D increments in IOL ability

Approximately 12 to 15 million patients receive an IOL implantation each yr.²⁵ These patients are becoming increasingly more demanding of higher-quality vision. Advances in surgical technique, better biometry, fourth-generation IOL adding formulae, and contempo advances in IOL blueprint and manufacture take enabled surgeons to routinely achieve a high standard of outcomes.

The International System for Standardization (ISO)²⁵ has aided by setting standards for IOL manufacturing tolerances. The ISO benchmarks, however, have non been recently updated and tolerate a wide range of variability (Table i). Although all manufacturers claim to exceed these tolerances,²⁵ Lenstec'southward range of accepted variability is smaller. The Softec Hd aspheric lens seeks to create the virtually authentic aspheric IOL, available in 0.25 D increments from 18.00 to 25.00 D. It is also bachelor in 0.l D increments from ten.50 to 29.50 D and 1.00 D increments from 5.00 to 36.00 D.

Table 1

ISO manufacturing tolerance for IOLs versus Lenstec tolerance

Range of diopteric effect	ISO permitted tolerance	Softec Hard disk lens
0 to ≤xv D	±0.iii D	±0.125 D
>15 to ≤25 D	±0.iv D	±0.125 D
>25 to ≤xxx D	±0.5 D	±0.125 D
>30 D	±1.0 D	±0.125 D

Lenstec preclinical studies

Lenstec Inc. performed nonclinical studies on this device in accordance with the ISO 11979 standards for IOLs.²⁶

Biocompatibility studies

Lenstec Inc. conducted a series of in vivo and in vitro acute and chronic toxicity tests to establish the biocom-patibility of the lens materials. In summary, the IOL material was nonmutagenic, nongenotoxic, nontoxic, and nonirritant subsequently muscle implantation. The IOL was photostable and nonextractable with a low level of aluminum.

Laboratory studies and manufacturing

Data from engineering analyses demonstrate the suitability of the material and overall device design for employ in IOLs. In summary, dioptric power, imaging quality/resolution, and spectral transmittance were within acceptance criteria. All lenses had an MTF value of greater than 0.43. All dimensions and compression forces were within the designed credence criteria. In an eye model, average axial displacement was 0.1 mm, boilerplate decentration was 0.152 mm, and average optic tilt was one.58°.

FDA clinical studies in the United states²⁶

The multicenter U.s. Lenstec Softec HD Posterior Sleeping accommodation Intraocular Lens (PCIOL) Clinical Investigation was conducted at viii clinical centers with Softec Hard disk PCIOL implantations occurring between December 13, 2006 and June nine, 2008. One yr postoperative follow-up provides documented testify of the safe and effectiveness of the Softec Hard disk drive PCIOL in 390 eyes of 390 study subjects.

Safety results

The analysis of prophylactic was based on the cohort of 366 patients who were bachelor for the 12-month evaluation. The analysis of safety was based on agin event rates (Table 2).

Table 2

Cumulative adverse events (occurring at any fourth dimension during the written report)

Cumulative adverse result	Softec Hard disk drive incidence (%) N = 366	Food and Drug Administration filigree (%)
Hyphema	0.0	ii.2
Macular edema	0.8	3.0
Retinal detachment	0.0	0.3
Pupillary block	0.0	0.1
Lens dislocation	0.0	0.1
Endophthalmitis	0.0	0.1
Hypopyon	0.0	0.3
Surgical reintervention	0.0	0.eight

Effectiveness results

The analysis of effectiveness was based on visual acuity on 366 patients at the 12-month time point. Of those patients implanted with the Softec HD IOL, 97.1% achieved a best-corrected visual acuity (BCVA) and 96.four% overall visual vigil of xx/40 or better as compared with the FDA grid (historical controls of 96.7% and 92.5%, respectively. The rate of twenty/forty or meliorate visual acuity for the cohort population exceeded the FDA grid values (Table 3).

Table 3

Best-corrected visual acuity by historic period: all patients at 1 year

Age group (years)	Total	20/10 or amend		twenty/16 or improve		20/20 or amend		20/25 or better		20/30 or better		twenty/40 or amend		20/50 or ameliorate		20/80 or improve		20/100 or better		20/200 or better		20/200 or worse
		north	%	n	%	northward	%	n	%	n	%	n	%	n	%	n	%	n	%	n	%	n	%
<60	36	0/36	0	half-dozen/36	16.7	26/36	72.2	33/36	91.7	36/36	100	36/36	100	36/36	100	36/36	100	36/36	100	36/36	100	0/36	0
60–69	128	0/128	0	12/128	ix.4	85/128	66.4	110/128	85.9	125/128	97.7	127/128	99.2	127/128	99.2	127/128	99.2	127/128	99.ii	127/128	99.2	1/128	0.viii
seventy–79	155	0/155	0	4/155	2.half dozen	78/155	l.3	121/155	78.1	143/155	92.3	152/155	98.1	153/155	98.vii	154/155	99.4	155/155	100	155/155	100	0/155	0
lxxx and older	47	0/47	0	2/47	4.three	22/47	46.8	33/47	70.2	41/47	87.2	45/47	95.7	47/47	100	47/47	100	47/47	100	47/47	100	0/47	0
Total	366

Subgroup analyses

Additional condom analyses were conducted to look for trends that may not exist apparent from the overall analysis of the adverse event and best spectacle corrected visual acuity rates. The following clinical information were evaluated.

Best-corrected distance visual acuity: stratified past historic period (all eyes)

BCVA stratif ied past historic period (age groupings: <60 years; lx to <70 years; 70 to <80 years; and ≥80 years) at 12-month follow-upwards. Equally would be predictable, the proportion of eyes with BCVA ≥xx/40 decreased with age: <60 years (100%); 60 to <70 years (99.2%); lxx to <fourscore years (98.one%); and ≥80 years (95.vii%).

Best-corrected altitude visual acuity: stratified by adverse upshot

The sponsor performed an analysis of the best-corrected distance visual acuity stratified by the presence of any adverse result, or specifically for the presence of a haptic break.

The BCVA of subjects who experienced an adverse event equally compared with those who did not was worse with regard to proportion of twenty/40 or better vision. At i year, 87.5% in the adverse outcome group compared with 98.ix% in the non-adverse event group had BCVA of >twenty/xl. One hundred percentage of cases in the adverse consequence group could meet 20/50 or better compared with 98.9% in the non-adverse event grouping. For those 6 study subjects who experienced a haptic suspension at the time of the Softec Hd implantation and and so received a Softec PCIOL, the i year BCVA was really better compared with the total written report field of study population in the Softec HD cohort who did not experience a haptic break: 100% haptic suspension grouping; 98.4% not-haptic break group seeing 20/40 or meliorate. The occurrence of a haptic intermission had no impact on visual acuity.

All-time-corrected altitude visual acuity: stratified by preoperative ocular pathology

In the patient population, preoperative macular degeneration was nowadays in 3.i% and other pre-existing conditions existed in 30.5%. BCVA greater than twenty/xl was lower in those study subjects with preoperative ocular pathology (94.1%) compared with the group of study subjects with no preoperative ocular pathology (98.8%) at the study endpoint.

Best-corrected distance visual vigil: subtract of two or more lines

Forty-2 subjects were included in a dateline listing of a decrease of two or more than lines of BCVA. The altitude BCVA was twenty/40 or better in 34 of the 42 subjects (81.0%). A clinical diagnostic explanation for the decrease in BCVA of 2 or more lines was identified by the sponsor. Thirty- vii of 42 subjects (88.ane%) had a definitive clinical diagnosis that affected visual acuity. In the five cases with no definitive clinical explanation, the decreases in BCVA were as follows: 20/ten to 20/twenty (pre-op 20/xxx); 20/20 to 20/xxx (pre-op 20/25); 20/twenty to twenty/30 (pre-op xx/fifty); 20/25 to twenty/40 (pre-op xx/50); and 20/25 to 20/40 (pre-op 20/l).

Best-corrected distance visual acuity: stratified past investigator

There was no statistically pregnant difference among sites with regard to BCVA xx/forty or amend at 12 months (P = 0.24).

The future

There is an increasing expectation for the development of customized aspheric IOLs according to spherical aberration and patient pupil size. With more than hydrophilic IOLs launching in the US market, at that place is anticipation of the marketing of rolling IOLs. Rolling IOLs can be inserted through a 2 mm incision or smaller, thereby increasing the popularity of microincision cataract surgery.

Unfortunately, as of yet, no clinical study has been conducted with the Softec HD IOL to assess the effect of the aspheric surface on spherical abnormality, contrast sensitivity, and visual acuity in different distances and compare this lens with other types of aspherical and spherical IOLs in a randomized clinical trial. Such a future report would allow clinicians to have bachelor to them the information needed to cull an appropriate IOL for each patient.

Footnotes

Disclosure

The authors accept no financial interest in any of the products discussed in this paper.

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Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3033005/