Faye Emery

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	In short: This article discusses the advantages and limitations for surgical compensation of presbyopia with the femtosecond laser using corneal inlays and the Intracor technique.

	By 2020, there will be around 2.1 billion presbyopes worldwide.

 It is unsurprising that there is a continuing interest in refractive surgical procedures that improve near vision.

	Both surgical interventions for presbyopia, and their contact lens counterparts, may reduce distance acuity, quality of vision, stereopsis or contrast sensitivity. Many also consider clear lens surgery too invasive, particularly in the early stages of the condition. Thus, there is significant interest in corneal inlays as they do not remove tissue; they preserve future options for presbyopic correction; they may be used in pseudophakia and/or combined with laser refractive surgery; they are removable; and they are only implanted within the non-dominant eye.

Related: Intracorneal inlays for the correction of presbyopia and low hyperopia

	There are three different corneal inlay types currently available: refractive optic inlays, which change the eye’s refractive index, providing distance vision through a plano central zone surrounded by one or more rings of varying add power for near vision; corneal reshaping inlays, which reshape the anterior curvature of the cornea to enhance near and intermediate vision via a multifocal effect; and small-aperture inlays, which rely on pinhole optics to increase depth of focus by blocking unfocused light.

	Only a small percentage of presbyopes are emmetropic; therefore, an additional LASIK might be performed in the case of a compound refractive error. Femtosecond lasers provide more predictable flap thickness, lower incidence of dry eye, faster visual recovery and better uncorrected distance visual acuity (UDVA) than mechanical microkeratomes.

 When a laser flap is created, many nerve-fibre bundles are cut; however, a pocket interface minimises the impact on the corneal nerves.

A clear, permeable hydrogel material makes up the Raindrop Near Vision Inlay (Revision Optics, Lake Forest, California, USA), which has around the same refractive index as the cornea (Figure 1).

 The inlay reshapes the central pupillary region of the non-dominant eye’s cornea to provide additional optical power relative to the unchanged peripheral region.

	Twelve-month results of 30 presbyopic patients after inlay implantation combined with myopic LASIK demonstrated that mean binocular UDVA, uncorrected intermediate visual acuity (UIVA) and uncorrected near visual acuity (UNVA) were better than 0.1 logMAR (20/25), and 93% of patients had binocular visual acuities better than 0.1 logMAR across all visual ranges.

	Patient questionnaires also showed that, 1 year after surgery, visual symptoms were at preoperative levels, 98% of all visual tasks could be easily performed without correction and 90% of patients were at least ‘satisfied’ with their overall vision.

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	Twelve months after implantation combined with hyperopic LASIK, mean UNVA in the surgical eye (n=16) improved from 0.8 logMAR preoperatively to 0.0 logMAR (patients gained a mean of >7 lines of UNVA).

 The mean binocular gain in UNVA was also seven lines. The UDVA in the surgical eye significantly increased from 0.5 logMAR to 0.2 logMAR and performed even better binocularly. There were no reported visual symptoms.

	The Flexivue Microlens (Presbia, Los Angeles, CA, USA), based on the InVue lens, is a transparent hydrophilic disk with a central 1.6 mm diameter plano disk and a peripheral zone that provides near addition power. The lens material’s refractive index is 1.4583 and it features a 0.51 mm central hole to facilitate the transfer of oxygen and nutrients to the cornea.

The Icolens system (Neoptics AG, Huenenberg, Switzerland) comprises a microlens with a positive refractive power, a femtosecond laser (Femto LDV, Ziemer Ophthalmic Systems AG, Port, Switzerland) with pocket-cutting algorithm, preloaded deployment device and purpose-designed positioning instruments. The Icolens is based on a similar design to Flexivue, with a central hole. Its copolymer has hydrogel properties and a refractive index of 1.460 in hydrated conditions.

	Short- to mid-term results and biocompatibility

	The Flexivue Microlens : Limnopoulou et al. 

 reported a significant increase in monocular and binocular UNVA (n=47). However, it should be noted that UDVA in operated eyes significantly worsened from 0.06 logMAR to 0.38 logMAR, maintaining stable binocular values. The mean refraction changed from 0.66 D to -1.95 D. No complications, removal or replacement occurred.

	In a different study, postoperative slitlamp examinations showed clear corneas in 52 patients without evidence of thinning, scarring or vascularisation , with well-centered inlays at all timepoints.

 reported 12-month results after monocular implantation in emmetropic patients. Mean UNVA in the surgical eye (n=52) improved from 0.78 logMAR to 0.44 logMAR postoperatively, and patients gained a mean of 3.48 lines. The UDVA in the surgical eye significantly worsened (mean loss of 1.67 lines) but, binocularly, could be maintained. In total, 90% of patients reported being satisfied with the overall procedure.

KAMRA inlay highly anticipated in 2016: Find out what else is coming!

	The KAMRA inlay (AcuFocus Inc, Irvine, CA, US) is approved in >50 countries outside the USA, with >20,000 inlays implanted today worldwide. The current generation (model ACI7000PDT) is a 5 μm thin microperforated artificial aperture, with a total diameter of 3.8 mm and a central aperture of 1.6 mm, made of polyvinylidene fluoride with incorporated nanoparticles of carbon. The opaque permeable material has a light transmission of 6.7% and a pseudorandom microperforation pattern (consisting of 8,400 holes); it allows water and nutrient flow.

	The longest follow-up to date (5 years; n=32), showed that mean binocular uncorrected visual acuities improved as follows: UNVA from 0.4 logMAR to 0.1 logMAR and UIVA from 0.2 logMAR to 0.1 logMAR.

 The UDVA decreased from -0.2 logMAR to -0.1 logMAR. One inlay was removed after 36 months because the patient was dissatisfied with vision after a hyperopic shift in the surgical eye.

More news: Intracorneal inlays for the correction of presbyopia and low hyperopia

It has been suggested that the ability to perform common daily tasks without glasses may be a better indicator of functional success than actual visual acuity. After 12 months, mean reading distance changed from 46.7 cm to 42.8 cm, and the mean reading acuity “at best distance” improved from 0.33 logRAD (reading equivalent of logMAR) to 0.24 logRAD. Mean reading speed and the smallest readable print size also improved.

 reported that KAMRA inlay subjects demonstrated improved intermediate and near vision with minimal to no change to distance vision, better contrast sensitivity in the inlay eye when compared with the multifocal lenses, and better binocular contrast sensitivity when compared with accommodating and multifocal IOLs.

	Visual simulations of the KAMRA corneal inlay suggest that the device extends depth of focus as effectively as traditional monovision in photopic light, in both cases at the cost of binocular summation.

 suggested that the best depth of focus in KAMRA patients can be obtained with small residual myopia (-0.75 D to -1.0 D) in the inlay eye and a plano refraction in the fellow eye. The use of a small aperture significantly reduced the negative impact of monovision on stereopsis.

Effect of pupil size and retinal image brightness

 reported that pupil size does not influence visual acuity after KAMRA inlay implantation (n=584).

The effect of the KAMRA corneal inlay on the retinal image brightness in the peripheral visual field has also been evaluated by ‘implanting’ a KAMRA inlay into a theoretical eye model in a corneal depth of 200 microns, varying pupil size from 2.0 to 5.0 mm and field angles from -70° to 70°. For large field angles, where the incident ray bundle is passing through the peripheral cornea, brightness is not affected. For combinations of small pupil size (2.0 and 2.5 mm) and field angles of 20–40°, up to 60% of light may be blocked with the KAMRA.

	Corneal inflammation and iron deposition

	An early increase in stromal cell death and inflammation was shown 48 hours after surgery in rabbit eyes that underwent a femtosecond laser pocket creation and KAMRA insertion compared with eyes with pocket formation only. The difference disappeared by 6 weeks after surgery.

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	With the first-generation inlay (ACI7000), 18 (56%) eyes of 32 patients developed corneal iron deposition within 36 months after corneal inlay implantation.

Alterations in tear film thickness, its composition and corneal epithelial basal cell storage, resulting from changes in corneal topography, may be contributing factors. Corneal iron deposition was only observed in 1 of 24 patients after 18 months with the new KAMRA inlay design (ACI7000PDT). Reduced inlay thickness and an increase in the number of nutritional pores as well as the modified implantation technique may contribute to this decrease.

 (n=277) all age-stratified groups achieved a mean UDVA of 0.0 logMAR after simultaneous LASIK and KAMRA implantation. Group 1 (40 to 49 years), Group 2 (50 to 59 years) and Group 3 (60 to 65 years) gained 1 line, 2 lines and 3 lines, respectively, suggesting that taking age into account might help achieve optimum outcomes.

The INTRACOR procedure is a minimally invasive intrastromal compensation for presbyopia using a femtosecond laser (FEMTEC Laser System; Bausch+Lomb/Technolas Perfect Vision, Munich Germany).

 The basic pattern for presbyopia is a series of femto-disruptive cylindrical rings that are delivered, starting within the posterior stroma, at a variable distance from Descemet’s membrane, and extending through the mid-stroma to an anterior location at a predetermined, fixed distance beneath Bowman’s layer. Laser delivery does not impact the endothelium, Descemet’s membrane, Bowman’s layer, or epithelium. The net effect is a central steepening of the anterior corneal surface in a multifocal hyperprolate corneal shape.

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	The standard pattern consists of five rings,

 although it might also be modified by creating six rings or by placing eight additional radial intrastromal cuts in the midperipheral stroma.

The longest follow-up reported 36 month results of 20 presbyopic patients with mild hyperopia (modified pattern with 6 rings).

Patients were randomly divided into three subgroups to compare the effect of three different ring diameters of the additional placed sixth ring [1.8/2.0/2.2 mm (Groups A/B/C)]. Median UNVA increased from 0.7/0.7/0.7 logMAR (Groups A/B/C) to −0.1/0.1/0.1 logMAR 36 months after surgery. UDVA changed slightly from 0.1/0.2/0.1 logMAR to 0.2/0.3/0.1 logMAR. Loss of two lines of binocular CDVA was noted in 0/25/0% of eyes. Overall patient satisfaction with the procedure was 80%.

	Three case reports describe corneal ectasia after combining LASIK with INTRACOR.

 reported one patient treated bilaterally for hyperopia using LASIK and achieving stable vision. Three years after the last LASIK enhancement, INTRACOR was applied bilaterally. After the procedure, a severe loss in CDVA and in quality of vision occurred, associated with a topography pattern suggestive of isolated anterior central protrusion.

 reported a patient receiving unilateral INTRACOR for presbyopia, followed 2 years later by an additional excimer LASIK enhancement (SUPRACOR) on both eyes. The eye treated with INTRACOR followed by SUPRACOR LASIK developed marked ectasia topographically limited to the area altered by INTRACOR, whereas the fellow eye remained stable and still has no signs of ectasia.

 described histopathologic findings in a case of hyperopic LASIK (twice in both eyes) followed by bilateral INTRACOR correction. A deep anterior lamellar keratoplasty had to be performed in one eye, and microscopy of the corneal button revealed that the inner intrastromal incision crossed the LASIK interface and led to stromal bed dehiscence.

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	The additive effects on stromal corneal stiffness of the LASIK lamellar incision in the frontal plane and INTRACOR incisions in the sagittal plane may disturb the corneal structural stability and lead to a progressive over-relaxing effect on the residual stromal bed. Therefore, the combination of both procedures can not be recommended.

			R.L. Lindstrom et al., Curr. Opin. Ophthalmol. 2013; 24: 281-287.

			G.M. Kezirian and K.G. Stonecipher. J. Cataract Refract. Surg. 2004; 30: 804-811.

			M.Q. Salomão, R. Ambrósio Jr. and S.E. Wilson. J. Cataract Refract. Surg. 2009; 35: 1756-1760.

			M. Tanna, S.C. Schallhorn and K.A. Hettinger. J. Refract. Surg. 2009; 25(7 Suppl): S668-S671.

			P.M. Pinsky. Invest. Ophthalmol. Vis. Sci. 2014; 55: 3093-3106.

			E.B. Garza and Chayet A. J. Cataract Refract. Surg. 2015; 41: 306-312.

			A. Yoo et al., J. Refract. Surg . 2015; 31: 454-460.

			A. Chayet and E. Barragan Garza. J. Cataract Refract. Surg. 2013; 39: 1713-1721.

			G.D. Parkhurst et al., J. Refract. Surg. 2015; 31: 206-208.

			A. Malandrini et al ., J. Cataract Refract. Surg. 2014; 40: 545-557.

			D.I. Bouzoukis et al ., J. Refract. Surg. 2011; 27: 818-820.

			A.N. Limnopoulou et al ., J. Refract. Surg. 2013; 2: 12-18.

Articles

This article discusses the advantages and limitations for surgical compensation of presbyopia with the femtosecond laser using corneal inlays and the Intracor technique.

Presbyopia compensation with femtosecond laser

	Santen recently launched fixed-combination tafluprost and timolol (TAPTIQOM) in the United Kingdom.

	The recently developed, preservative-free, fixed-dose combination of 0.0015% prostaglandin F

 analog (tafluprost) and beta-adrenergic antagonist (0.5% timolol) is designed to lower intraocular pressure (IOP). TAPTIQOM® is available in single dose containers and is administered as one drop once-daily.

 in 2014, patients with high IOP responded well to TAPTIQOM®, which delivered IOP reductions of up to 40% (>13 mmHg) versus baseline and even beyond this in some cases. Specifically, two Phase-III studies (n=484) revealed that TAPTIQOM® delivered IOP reductions of between 28% and 40% (dependent on baseline) at 3 months. The 

 review included double-masked, controlled clinical trials carried out with the following combination products: Xalacom

 and TAPTIQOM® and found that the reduction in IOP was similar to that of other prostaglandin–timolol fixed-combination products used in open-angle glaucoma and ocular hypertension.

Reducing hyperaemia and improving tolerability

	Although questions have been raised in the ophthalmic community around the benefit of adding a further combination product with similar efficacy to the market, The European Glaucoma Society 2014 guidelines do state that when selecting glaucoma therapy, consideration should be given not only to IOP lowering but also to tolerability, adherence and cost.

	Despite similar IOP-reducing capacities, when compared to previous controlled and double-masked clinical trials with DuoTrav

 (Allergan, Irvine, USA), the review revealed that TAPTIQOM® caused fewer superficial ocular side effects and less conjunctival hyperaemia. Indeed, the frequency of reported treatment-related adverse event conjunctival / ocular hyperaemia in clinical studies was low (7% of patients). In addition, in the small number of TAPTIQOM® treatment-related hyperaemia cases, the condition was mild and was associated with discontinuation of therapy in just 1.2% of patients.

	The mechanism of IOP reduction is similar for all the combination products that were assessed in the review; timolol induces the reduction of aqueous humor production, and the enhancement of aqueous humor outflow occurs via FP prostanoid receptor activation, induced by the prostaglandin.

	Plausible explanations for the differences in side effects between the fixed-combination products are as follows:

	·       All prostaglandin analogs are rather selective FP prostanoid receptor agonists, however, some subtle differences do exist, which may explain the variance in side effects. As timolol is well known for inducing no or minimal hyperaemia (or irritation), it seems probable that the condition is caused mainly by the prostaglandin analog. Unlike the other combinations reviewed, TAPTIQOM® stimulates EP

 receptors, which can be expected to cause vasoconstriction and thereby counteract part of the vasodilation caused by the FP receptor stimulation, explaining why the hyperaemia caused by TAPTIQOM® appears to be less frequent and less severe than that of Ganfort

	·       TAPTIQOM® are preservative free drops – this feature could be what causes the eye drops to exert relatively little ocular irritation. On the other hand, taking into account the relatively short period of exposure, it is as likely that the improved tolerability profile of TAPTIQOM® is due to the active ingredient. Nevertheless, the absence of preservative will certainly improve the long-term tolerability of TAPTIQOM®. It is important also to bear in mind that European Glaucoma Society 2014 guidelines also highlight that the chronic use of medications containing preservatives may cause or exacerbate ocular surface disease.

	TAPTIQOM has been approved in Germany since December 2014 for adults with open-angle glaucoma or increased IOP (ocular hypertension) and is now indicated in the UK for the IOP reduction in adult patients with open-angle glaucoma or ocular hypertension 

who are insufficiently responsive to topical monotherapy with beta-blockers or prostaglandin analogues and require a combination therapy

, and who would benefit from preservative free eye drops.

	Craig Wallace, Santen General Manager UK & Ireland believes that TAPTIQOM® now offers the next step in preservative-free IOP reduction because it combines powerful efficacy with good ocular tolerability, which supports patient adherence to therapy and is an ideal solution for patients who are insufficiently responsive to topical monotherapy with prostaglandin analogues or beta-blockers, requiring combination therapy. The drug may hold particular promise for patients with hyperaemia in particular, a common side effect of anti-glaucoma therapy and a key reason for patients discontinuing treatment with prostaglandin analogues. TAPTIQOM ® also offers the benefit of being competitively priced in the UK.

Santen recently launched fixed-combination tafluprost and timolol (TAPTIQOM) in the United Kingdom.

Santen launches new preservative-free combination eye drop in the UK

	Take-home message: This follow-up study found anterior capsule opacification development and anterior capsule retraction to be more frequent 3 years after cataract surgery when an IOL with interrupted sharp optic edge at the optic–haptic junction is implanted, compared with an IOL with a continuous edge.

	By Faye Emery; Reviewed by Dr Guenal Kahraman

Dr. Guenal KahramanThe material and design of intraocular lens’ (IOL), especially at the optic edge, are both relevant factors when it comes to anterior (ACO) and posterior capsule opacification (PCO) development.1–4 Sharp optic edges have previously been shown to prevent migration of epithelial cells between the capsular bag and the IOL.1–3 In this study, the authors evaluated and compared the degree of PCO, ACO and anterior capsule retraction, 3-years after implantation of 2 different single-piece hydrophobic acrylic IOLs. One of the implanted lenses featured a 360-degree continuous sharp optic edge (Tecnis ZB00, Abbott Medical Optics, Inc., Illinois, USA) whereas the other had an interrupted square edge (Acrysof SA60AT, Alcon Surgical, Inc., Surrey, UK).

	Between October 2009 and September 2013, 80 patients who had previously undergone uneventful phacoemulsification with bilateral senile cataract that induced a significant visual deterioration were enrolled in the study at the Hospital of St. John of God (Vienna, Austria).5 Each patient randomly received 1 IOL model in 1 eye and the other model in the fellow eye by the same surgeon.

	During follow-up visits, a complete ophthalmologic examination including slitlamp biomicroscopy, applanation tonometry, and fundus examination were performed. The ACO grading was carried out subjectively with a slitlamp by 1 experienced examiner. The Evaluation of Posterior Capsule Opacification (EPCO) software developed by Tetz et al.6 was used to quantify PCO.

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	During the final follow-up visit, 3-years post-implantation, the investigators were able to analyse images of 50 patients (100 eyes) out of the original 80 (Figures 1-3). Patient age ranged from 61 to 80 years with a mean value of 70.2 years ± 9.3 (SD).

(Figure 1) Scattergram showing the relationship between the PCO level 3 years postoperatively in eyes implanted with the Acrysof IOL (group A), and eyes implanted with the Tennis IOl (group B). Each circle corresponds to one patient.

	No significant differences in PCO score were found between Acrysof IOL and Tecnis IOL. (3 year follow-up visit: Acrysof 0.23 ± 0.36 versus Tecnis 0.22 ± 0.32, P = 0.66). Anterior capsule opacification was present in Acrysof 18.0% and Tecnis 2.7% (P = 0.03) and in 92.0% and 24.0% of eyes (P < 0.01) at 1 and 3 years after surgery, respectively.

	The authors noted that low mean PCO scores were obtained with both types of IOL, with no significant differences between them throughout the follow-up period. It was suggested that IOL material was a crucial factor for the observed low levels of PCO. However, when it came to analysing the ACO results, outcomes were very different to those found for PCO. Significantly higher percentages of ACO and overall higher scores were observed in eyes implanted with the interrupted square optic edge IOL compared to those implanted with the continuous square optic edge IOL. As each type of IOL was implanted in fellow eyes of the same patient (thus the study was an intraindividual comparison), the authors suggested differences in IOL surface properties and design as an explanation for this finding.

	(Figure 2) Frontal biomicroscopic image showing one case of moderate ACO (Grade 3) in an eye implanted with the Acrysof IOL.

	(Figure 3) Distribution of the level of ACO in the two evaluated groups

	The Acrysof SA60AT is a biconvex IOL with a 0-degree haptic angulation whereas the Tecnis ZCB00 is a biconvex IOL with an offset haptic design, providing 3 points of fixation. The interruption of the square optic edge at the optic–haptic junction as well as the configuration of the IOL optic surface may promote or facilitate the migration of lens epithelial cells (LECs) to the space between the anterior capsule and the IOL (Figure 4). The sharp posterior edge inhibits migration of anterior capsule LECs behind the optic, therefore resulting in slightly stronger ACO. The gunnel, a kind of circular groove in the periphery of the Tecnis ZCB00 IOL might further prevent LECs to migrate on the anterior surface of the IOL. A better understanding into this association could possibly be gleaned following further studies into the potential impact of this design on the developmental process of ACO.

	The authors also proposed that the opacification of the anterior and posterior capsule seem to be simultaneous processes in eyes that are implanted with a square optic edge IOL. This proposal was fuelled by the significant increase observed in the level of ACO throughout the follow-up, as was also found for the level of PCO.

	“Our study is one of the first papers which shows that the design is more important than material. As both study IOLs are made of almost same material, I believe the design of the IOL is crucial.” Dr Kahraman explained.

	In response to the study results, the authors concluded that there was no statistically significant difference in PCO rate between the 2 IOL models after 3 years. However, the ACO development and anterior capsule retraction was significantly higher at the Acrysof group.

	Dr Kahraman added that “a certain amount of ACO is desirable. We know that ACO might reduce the dysphotopsia and PCO, but severe ACO would cause IOL decentration and affect visual quality.”

	As IOLs were implanted in fellow eyes of the same patient and the two IOLs evaluated in the study were made of hydrophobic acrylic material, the factors inherent in the individual patient can be disregarded. Specifically, differences in IOL surfaces properties and design could explain the difference between IOLs in the ACO rate. Different anterior capsule behaviour is present postoperatively in eyes implanted with IOLs with a 360º continuous sharp optic edge compared to those without. The retraction of the anterior capsule might increase the shrink-wrap effect of the capsular bag and which might reduce the PCO formation. It is debatable whether it is indeed desirable to reduce the risk for PCO at the expense of a higher rate of ACO and capsule retraction.

	To summarise the article findings, the authors believe that the design of the IOL is the key reason behind the observed rates of ACO in this particular study.

2015; pii: S0886-3350(15)00426-5. doi: 10.1016/j.jcrs.2014.07.041.

	Dr Guenal Kahraman is consultant ophthalmic surgeon at the Academic Teaching Hospital of St John, Krankenhaus der Barmherzige Brüder,  Vienna, Austria.

	The author has no financial disclosures relating to the content of this article.

This follow-up study found anterior capsule opacification development and anterior capsule retraction to be more frequent 3 years after cataract surgery when an IOL with interrupted sharp optic edge at the optic–haptic junction is implanted, compared with an IOL with a continuous edge.

Faye Emery

Articles

Presbyopia compensation with femtosecond laser

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Capsule opacification with 2 different IOLs: 3-year results

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