Opth-23147-visual-perception-changes-and-optical-stability-after-icrs-i

Clinical Ophthalmology
open access to scientific and medical research stability after intracorneal ring segment This article was published in the following Dove Press journal: Clinical Ophthalmology28 July 2011Number of times this article has been viewed Purpose: To prospectively evaluate intracorneal ring segment (ICRS) implantation on quality
of life (QoL) of patients with keratoconus changes and identify factors responsible.
Methods: Sixty-nine eyes of 42 keratoconus patients were implanted with the Keraring
(Mediphacos, Belo Horizonte, Brazil). Best corrected visual acuity (BCVA), refraction, and steep keratometry were analyzed 3 months and 1 year after surgery. All patients self-administered the National Eye Institute Refractive Error Quality of life instrument at 2 time points: after having worn best correction for at least 30 days since evaluation (mean 4 months after surgery)
and 1 year after surgery. To analyze if the use of the appropriate correction at 1 year follow
up had any impact on visual acuity and V-QoL, patients were divided into 2 groups: group A
(appropriate correction) and B (not appropriate correction).
Results: After 1 year, QoL changes related to scales ‘clarity of vision’, ‘near vision’, and
‘far vision’. Keratometric values, sphere, and spherical equivalent did not differ significantly
between 3 months and 1 year postoperative. Cylinder increase was statistically but not clini-
cally significant. Binocular BCVA did not change 1 year after surgery in group A and showed
a clinically significant impairment in group B. A year after surgery, 18 patients did not use
correction suggested by a physician 3 months after surgery. QoL was not statistically different
1 year after surgery between group A and group B.
Conclusion: Our findings show that the way keratoconic patients see is difficult to analyze
using only quantitative and 1-visit metrics. They highlight the importance of patients’ self
perception and performing longitudinal analysis to consider neural compensation to optical
changes from surgery.
Keywords: keratoconus, cornea, quality of life
Introduction
Keratoconus is a chronic disease affecting young people. Early symptoms are usually
noticeable in the early 20s.1 The disease is progressive and vision may be seriously
impaired, causing an important negative impact on patients’ quality of life (QoL).2
In the early stages, vision can be improved by the use of spectacles but with disease
progression contact lenses or surgery are necessary to restore vision.
Penetrating keratoplasty is the most common surgery to treat keratoconus. This yields good results but with potential complications including graft failure, rejection, glaucoma, irregular astigmatism, cataract, and glare.1,3,4 Rehabilitation for 1 year usually follows surgery.3 Intracorneal ring segment (ICRS) implantation is a surgical option submit your manuscript
Clinical Ophthalmology 2011:5 1057–1062 2011 Paranhos et al, publisher and licensee Dove Medical Press Ltd. This is an Open Access article which permits unrestricted noncommercial use, provided the original work is properly cited.
to avoid corneal graft. It has an arc-shortening effect and For all surgeries the 160° Keraring (Mediphacos, Belo so the central portion of the cornea tends to flatten and the Horizonte, Brazil) was implanted with thickness varying peripheral area adjacent to ring insertion is displaced forward. from 150 to 350 µm. Vigamox solution (moxifloxacin HCl Because the procedure does not involve tissue removal it has ophthalmic solution 0.5%, Alcon Inc, Fort Worth, TX) was fewer intraoperative and postoperative risks and faster vision instilled 4 times, 1 hour before surgery, and pilocarpine rehabilitation, of about 3 months after surgery.5–9 (pilocarpine hydrochloride 10 mg/mL, Allergan Inc, Irvine, A study conducted by the CLEK group2 concluded CA) once before surgery. The surgery was performed under that QoL is seriously affected in keratoconus patients and topical anesthesia (proxymetacaine chlorhydrate 0.5%, continues to decline over time, but an earlier study by our Anestalcon, Alcon). Polyvinylpyrrolidone-iodine (PVPI, group showed that ICRS implantation improves visual Ophthalmos, Inc, São Paulo, Brazil) was used over the conjunctiva and cornea 5 minutes before surgery. A circular The National Eye Institute Refractive Error Quality of marker centered on the reflex of microscope light on the Life (NEI-RQL) is a vision-targeted survey to assess the cornea was used to create 2 concentric circles of 5 and 7 mm. impact of refractive error and its correction on day-to-day A radial incision set at 80% of the corneal pachymetry at the life.11 The purpose of this study is to prospectively evaluate steepest corneal axis was made, then 1 or 2 concentric stromal if V-QoL changes 1 year after ICRS implantation and to tunnels with an internal radius of 2.5 mm and an attempted identify the factors responsible for any changes that occur.
extension of 170° were constructed with an appropriate curved spatula, and the ring segments implanted in these Materials and methods
tunnels. After surgery patients were instructed to use topical antibiotics and corticosteroids (Vigamox eyedrops 3 times a Ophthalmologists of Goiânia, Goiás, Brazil working in the day for 7 days and prednisolone acetate 1%, Falcon, 4 times Department of Ophthalmology of the Federal University of Goiás were asked to refer patients with keratoconus indicated for ICRS implantation. Indications for ICRS implantation were poor visual acuity with spectacles, intolerance to contact Refraction, slit lamp biomicroscopy, indirect ophthalmoscopy, lenses, steep keratometric reading ,70 diopters (D), and and corneal topography (Medmont) were evaluated at 2 time clear central cornea. Patients who had never tried contact points: 3 months and 1 year after surgery.
lenses were tested and, if lenses fitted well, the patients were Best corrected visual acuity (BCVA) with current correction (spectacles, contact lenses, or no correction) of operated eyes and binocular BCVA were assessed when patients had been wearing their best correction for at least Patients included in this study were aged 19 to 39 years. 30 days after initial post-surgical evaluation (mean 4 months They had keratoconus in both eyes, symmetrical or asym- after surgery) and 1 year after surgery. The LogMAR chart metrical, diagnosed by corneal topography with clear central corneas, poor visual acuity with spectacles, and intoler- Keratoconus patients self-administered a Portuguese ance to contact lenses.1 The steepest keratometric value validated version of the NEI-RQL instrument.12 Patients answered the survey after ICRS implantation (Keraring), when they had been using best correction for at least 30 days after evaluation (mean 4 months after surgery) and 1 year Patients were excluded from the study if they had other ocular after surgery. The survey consisted of 42 items used to diseases besides keratoconus, if they had systemic conditions build 13 scales (clarity of vision, expectations, near vision, with a potential to cause refractive instability (pregnancy, far vision, diurnal fluctuations, activity limitations, glare, diabetes), or if they were illiterate.
symptoms, dependence on correction, worry, suboptimal correction, appearance, and satisfaction with correction), surgical technique and postoperative care which were transformed linearly to a 0 to 100 possible range. All surgeries were performed by the same surgeon (JFSP) in Lower scores corresponded with lower or worse QoL on 2007 between June and October. The manufacturer’s nomo- each subscale. The NEI-RQL was scored according to the gram was used to calculate the implantation of the ICRS. submit your manuscript |
The patient data were first analyzed all together. Then and 1 year (mean 52.84 ± 0.63) after surgery (P = 0.4715). patients were divided into 2 groups: group A included patients Sphere and spherical equivalent data did not show any sta- who were wearing the appropriate correction as suggested tistically significant change between these 2 time points after by their physician and group B included patients who were surgery (P = 0.269 and P = 0.075 respectively). Cylinder had not using the suggested correction at 1 year.
a statistically but not clinically significant increase 1 year after ICRS implantation (P = 0.014) (Table 1).
The treated eyes decreased by 1 line of BCVA 1 year This study was approved by the ethics committees of the after surgery (0.25 [0.02] to 0.34 [0.03] P = 0.0091), which Federal University of Goiás and Federal University of São is statistically significant. Mean binocular BCVA also had a Paulo. All patients read and signed consent forms.
statistically significant worsening (0.07 [0.14] to 0.14 [0.17] P = 0.021).
Of the 42 patients, 36 (85.7%) had data related to cor- Paired t and Mann–Whitney nonparametric tests were used rection in current use 1 year after surgery. Eighteen (50%) to compare binocular BCVA and NEI-RQL scales twice after patients wore a correction different from that suggested by surgery. For measurements taken per eye (sphere, cylinder, a physician 3 months after surgery (Table 2). Twenty-four spherical equivalent, steep keratometric reading [K ] and (66.7%) patients did not need to change their initial correction visual acuity), generalized estimation equation models were 1 year after surgery. Of the 14 patients who were not using applied in order to take the within-subject correction into any correction 1 year after surgery, 12 actually needed to use account. Analysis of variance was used to compare groups some form of correction (9 spectacles, 2 soft contact lenses, A and B in order to evaluate whether use of adequate cor- and 1 patient, rigid gas permeable lenses).
There was a statistically significant reduction in the scores The level of significance adopted was 0.05. Statistics of the scales related to clarity of vision, near vision, and were calculated using SPSS for Windows software, version far vision (Table 3). The QoL of these scales had a signifi- cant worsening 1 year after surgery (P = 0.703, P = 0.892, P = 0.263, respectively). The scores of the other scales and the general scale did not have a statistically significant dif- Forty-two patients were included in this study and answered ference between the 2 times of evaluation (P . 0.05).
the questionnaire 4 months after surgery, of which 33 (78.6%) There was no statistical difference between QoL scales returned and answered the questionnaire 1 year after surgery. in groups A and B 1 year after surgery. The results of these Of the 9 patients that did not have QoL data 1 year after 2 groups for QoL in the scales of clarity of vision (P = 0.703), surgery, 6 did not return to be examined, 1 did not answer the near vision (P = 0.892), and far vision (P = 0.263), 1 year questionnaire, and 2 had ring extrusion. Of the 42 patients, after surgery, were similar. Visual acuity was different in 19 (45.2%) were male and 23 (54.8%) were female. The these 2 groups (P = 0.047). Group A had no difference in average age was 24.9 ± 5 years (range 18 to 39 years). Most binocular BCVA between 4 months and 1 year after surgery patients (66.7%) were undertaking or had completed high (0.10 [0.15] to 0.12 [0.14] P = 0.189) and group B had an school, 26.2% were at university, and 7.1% had received almost statistically significant worsening (0.01 [0.09] to 0.19 [0.24] P = 0.053). Group B lost 2 lines in mean binocular Twenty-seven, of the total of 42 patients, had surgery BCVA, which was clinically significant (Figure 1).
in both eyes and the rest underwent surgery in only 1 eye, representing a total of 69 eyes with ICRS implantation. Table 1 Comparison of sphere, cylinder, spherical equivalent and
Twelve patients had surgery performed only in 1 eye due to K 3 months and 1 year after Keraring iCrs implantation good vision in the other eye. Three patients did not meet the 3 months after surgery 1 year after surgery P-value
criteria for ICRS implantation in their other eye and these Mean (SD)a
Mean (SD)a
eyes had a significant visual acuity impairment.
Data were analyzed from the 33 patients with complete data, who had returned 1 year after surgery.
There was no statistically significant change in steep Notes: aCorrection within subjects was taken into account; K = steep
keratometric (K ) reading 3 months (mean 52.64 ± 0.67) submit your manuscript
Table 2 Comparison between patients’ current correction 4 months and 1 year after iCrs implantation
Correction in use 1 year after surgery
Spectacles
Soft lenses
Abbreviations: iCrs, intra-corneal ring segment; rgP, rigid gas permeable.
Discussion
adaptive optics. The magnitude of their response to the Neural compensation occurs in keratoconus patients due to correction of higher-order aberrations was different from long-term optical blur. A study showed that due to neural that expected and they did not achieve the visual benefit compensation keratoconus patients had statistically better predicted.14,15 Therefore the assessment of V-QoL through high and low contrast visual acuity than those with normal questionnaires like NEI-RQL can be used as a suitable tool vision exposed to keratoconic aberrations with the use of to analyze the impact of optical changes in keratoconic eyes due to surgical procedures.
This was a longitudinal prospective study that evaluated Table 3 Comparison between nei-rQL scores 4 months and
1 year after Keraring iCrs implantation
ICRS implantation results at 2 time points: 4 months and 1 year after surgery. Sphere and spherical equivalent did not 1 year after
P-value
change 1 year after surgery (P . 0.05). Cylinder increase in this period was statistically but not clinically significant (1.78D [0.18] to 1.98D [0.16]; P = 0.014). There was no statistical significant change in mean steep keratometric readings (K ) (52.64 [0.67] to 52.84 [0.63]; P = 0.4715). The operated eyes lost a mean of 1 line of BCVA 1 year after surgery. One year after surgery, 50% of the patients were not using the correction (group B) suggested by their physi- cian 3 months after surgery. So, except for the difference in Abbreviations: iCrs, intra-corneal ring segment; nei-rQL, national eye institute
Figure 1 Quality of life answers for mean binocular best corrected visual acuity
submit your manuscript |
visual acuity between groups A and B there was no other subjective outcomes of Keraring ICRS implantation over important optical change in these patients 1 year after ICRS 1 year and the results showed that general V-QoL is sustained over this period. Of the 13 scales, only 3, clarity of vision, Quality of life changed 1 year after Keraring implan- near vision, and far vision, showed significant worsening tation in relation to NEI-RQL scales ‘clarity of vision’, 1 year after surgery, although they still presented high scores ‘near vision’, and ‘far vision’. There was no difference in (.70 points), showing that V-QoL remained good.
V-QoL between group A (using the correction suggested by physician and no visual acuity changes) and B (using a Disclosure
different correction and 2 lines lost) even in scales of clarity None of the authors have any financial interests in other of vision (P = 0.703), near vision (P = 0.892), and far vision products or techniques described herein.
(P = 0.263), showing that visual acuity did not influence subjective results. These results consolidate previous findings References
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