Does the Stage of Keratoconus Affect Optical Coherence Tomography Measurements?

Uzunel, Umut Duygu; Küsbeci, Tuncay; Yüksel, Bora

doi:10.3109/08820538.2016.1169302

Cited by 18 publications

(29 citation statements)

References 29 publications

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“…The results showed that both RNFL and GCC measurements were comparable between the keratoconus and control groups. The control participants had slightly higher global RNFL thickness measurements than the keratoconus participants (106 µm vs. 99 µm and 103 µm vs. 98 µm for the right and left eyes respectively), but these 36 reported that these thickness differences were statistically significant (p < 0.001). Unlike in the present study, Uzunel et al 36 separated their participants with keratoconus (n = 68) into three grades, using the Amsler-Krumeich classification system, and analysed the different mean global RNFL measurements for each grade of keratoconus which may explain this difference.…”

Section: Discussionmentioning

confidence: 91%

Retinal nerve fibre layer and ganglion cell complex thickness in patients with keratoconus

Cuppusamy

Makhanya

Methula

et al. 2018

Afr. vis. eye health

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Background: Keratoconus, a corneal ectasia, is associated with corneal thinning and altered optical media. Consequently, assessment of the visual field, optic nerve head and intraocular pressure measurements may be challenging in patients with keratoconus. Few studies have investigated posterior segment variables including the retinal nerve fibre layer (RNFL) and ganglion cell complex (GCC) thickness in patients with keratoconus.Aim: To investigate RNFL and GCC thickness in patients with keratoconus.Methods: A comparative quantitative research design was used. The sample consisted of 56 participants (28 with mild, moderate or severe keratoconus, and 28 controls) who accessed the optometry clinic at the University of KwaZulu-Natal. There was an equal distribution of male (n = 14) and female (n = 14) participants in the keratoconus and control groups. Most participants were black (n = 34) or Indian (n = 18). Corneal power and refractive error were assessed with the Oculus Keratograph and subjective refraction respectively. The iVue-100 optical coherence topography device was used to measure RNFL and GCC thickness. Data were analysed by descriptive and inferential statistics.Results: The mean global RNFL thickness was slightly higher in the control group than the keratoconus group for the right (106 µm vs. 99 µm) and left (103 µm vs. 98 µm) eyes but these differences were not significant (p ≥ 0.057). For all RNFL quadrants, slightly lower mean RNFL measurements were found in the keratoconus group. The mean GCC thicknesses were marginally higher (3 µm – 6 µm) in the control group.Conclusion: The RNFL and GCC thickness differences between patients with keratoconus and controls are not clinically significant. Therefore, abnormally reduced RNFL and GCC thickness measurements in patients with keratoconus warrant further investigation for other pathologies specifically glaucoma.

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Section: Discussionmentioning

confidence: 91%

Retinal nerve fibre layer and ganglion cell complex thickness in patients with keratoconus

Cuppusamy

Makhanya

Methula

et al. 2018

Afr. vis. eye health

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“…Among the 360 graft-host sections, confined to only keratoconic eyes in the current study, the most common malapposition was graft step (122 cases, 33.9%). Since it has been reported that preoperative corneal pathology can influence the graft-host apposition patterns, 14,16 we hold the opinion that asymmetrical pre-operative thinning of the cornea in different disease stages caused increased graft step numbers, because the normal corneal grafts from donors were generally thicker than the recipient beds, which had already thinned.…”

Section: Discussionmentioning

confidence: 93%

Malapposition of Graft-host Interface after Penetrating Keratoplasty (PK) and Deep Anterior lamellar Keratoplasty (DALK): an optical coherence tomography study

Zhao¹,

Zhuang²,

Hong³

et al. 2020

Preprint

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Backgroud: Previous studies of internal graft-host malappositions have not dealt with the precise ways in which each malapposition affected post-penetrating keratoplasty (post-PK) visual outcomes. In this study, we reviewed our post-PK and post-deep anterior lamellar keratoplasty (post-DALK) keratoconic patients and used anterior segment optical coherence tomography (AS-OCT) to evaluate the associations between graft-host interface (GHI) characteristics and visual outcomes. Methods: Novel GHI metrics included: mean graft-host touch (GHT), total prevalence of malapposition proportion (Pm), frequency of apposition (F), size of malapposition (Sm), junctional graft thickness (Tg), junctional host thickness (Th) and the absolute value of difference between Tg and Th (|Tg-Th|). We connected the external and internal junction points of GHI (GHT) and drew a straight line through the central point, perpendicular to both sides of the cornea. Tg and Th were the thicknesses at cross-points 1 mm away from the meeting point on the external side of the graft and host, respectively. Linear regression analysis was used to describe associations between GHI metrics and postsurgical visual outcomes [ logarithm of minimum angle of resolution best-corrected visual acuity (logMAR BCVA), spherical equivalent diopter (SE), diopter of spherical power (DS), diopter of cylindrical power (DC) and keratometric astigmatism (Astig value)]. Results: We enrolled 22 post-PK and 23 post-DALK keratoconic patients. Compared with the regular-apposition results, GHT was decreased in step and gape patterns, and increased in hill and tag patterns. SE increased averagely by 6.851, 5.428 and 5.164 diopter per 1% increase in: F (step) [β=6.851; 95% Confidence interval (CI)=2.975-10.727; P=0.001]; F (graft step) [β=5.428; 95% CI=1.685-9.171; P=0.005]; and Pm [β=5.164; 95%CI=0.913-9.146; P=0.018], respectively. SE increased averagely by 0.31 diopter per 10-μm increment in |Tg-Th| [β=0.031; 95% CI=0.009-0.054; P=0.007]. LogMAR BCVA increased (on average) by 0.01 per 10-μm increment in both GHT [β=0.001; 95% CI=0-0.002; P=0.030]. and Tg [β=0.001; 95% CI=0.001-0.002; P=0.001]. Astig value increased on average by 0.17 diopter per 10-μm increment in Sm [β=0.017; 95% CI=0-0.033; P=0.047]. Conclusion: This investigation of GHI characteristics suggests explanations for varied ametropia in keratoconic eyes and has potential significance as a reference for promoting pre-surgical planning and technology for corneal transplantation.

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“…Surprisingly, our results showed no difference in image quality or macular thickness values between scans obtained from uncorrected astigmatic eyes and scans obtained from the same eyes with RGP contact lens correction. A previous study demonstrated that SD‐OCT‐derived parameters such as RNFL or central subfield thickness and mean signal strength were affected by irregular astigmatism 2017. Signal strength was affected significantly by refractive changes already in early stages of keratoconus 2015.…”

Section: Discussionmentioning

confidence: 96%

“…A previous study demonstrated that SD-OCTderived parameters such as RNFL or central subfield thickness and mean signal strength were affected by irregular astigmatism. 7,31 Signal strength was affected significantly by refractive changes already in early stages of keratoconus. 7 In other studies, RNFL thickness changes after astigmatism induction was statistically significant; however, the magnitude of change was minute.…”

Section: Discussionmentioning

confidence: 99%

The effect of contact lens wear on retinal spectral domain optical coherence tomography

Aviram

Beeri

Berkow

et al. 2020

Clinical and Experimental Optometry

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Background: This study assessed the impact of contact lens wear on retinal spectral domain optical coherence tomography (SD-OCT) image quality and macular thickness measurements, among subjects with myopia. Methods: This was a prospective study including 34 subjects (26.59 AE 3.19 years) with myopia or myopic astigmatism. Twelve were imaged wearing spherical soft contact lenses, eight non-contact lens wearers were imaged with a plano soft contact lens, and 14 with significant astigmatism were fitted with a rigid gas permeable (RGP) contact lens. For each group of contact lens types, the average image quality index (Q-index), and the average macular thickness measurements were compared between macular OCT scans obtained from the same eyes with and without a contact lens. Results: Among the subjects assessed with their habitual spherical soft lenses, the average Q-index was similar for scans acquired with and without a contact lens (30.10 AE 1.94 versus 31.03 AE 2.55; p = 0.18). Among non-contact lens wearers, the average Q-index was slightly higher for scans acquired without a contact lens, compared to scans with a plano contact lens (31.99 AE 2.06 versus 29.51 AE 1.56; p = 0.006). Among 14 subjects imaged wearing a fitted RGP contact lens, the Q-index was similar for scans acquired with and without a contact lens (29.04 AE 2.73 versus 28.75 AE 2.86; p = 0.78). In all groups, there were no correlations between the power of the sphere and change in the Q-index (that is, post-minus pre-contact lens Q-index), and no differences were found between OCT-derived macular thickness measurements from scans with and without a contact lens. The magnitude of cylinder was not correlated with the change in the Q-index in the habitual and RGP contact lens groups. However, an inverse correlation between cylinder power and change in the Qindex was found in the plano contact lens group. Conclusion: In low to intermediate levels of myopia, with or without regular astigmatism, macular SD-OCT imaging does not merit placement of a soft or rigid contact lens, nor is there an added benefit from removing a habitual spherical soft lens prior to scanning.

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Does the Stage of Keratoconus Affect Optical Coherence Tomography Measurements?

Cited by 18 publications

References 29 publications

Retinal nerve fibre layer and ganglion cell complex thickness in patients with keratoconus

Retinal nerve fibre layer and ganglion cell complex thickness in patients with keratoconus

Malapposition of Graft-host Interface after Penetrating Keratoplasty (PK) and Deep Anterior lamellar Keratoplasty (DALK): an optical coherence tomography study

The effect of contact lens wear on retinal spectral domain optical coherence tomography

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