Kristian Krøyer

Herlev Hospital, Herlev, Capital Region, Denmark

Are you Kristian Krøyer?

Claim your profile

Publications (5)17.33 Total impact

  • Article: Prognostic significance of delayed structural recovery after macular hole surgery.
    [show abstract] [hide abstract]
    ABSTRACT: To assess the prognostic significance for visual function of persistent subfoveal fluid and persistent photoreceptor layer discontinuity in eyes in which hole closure had been obtained 3 months after macular hole surgery. Ancillary study of subjects enrolled in a randomized clinical trial. Participants were recruited from a randomized clinical trial evaluating internal limiting membrane (ILM) peeling in macular hole surgery. The study included 74 eyes in which a contiguous retinal surface or a full attachment with a flat neuroretinal rim had been reestablished after macular hole surgery. Contrast-enhanced optical coherence tomography was used to detect closure defects involving substrata of the retina with particular emphasis on the photoreceptor layer. Outcomes were compared with best-corrected visual acuity (BCVA) 12 months after surgery. Postoperative foveal configuration and foveal photoreceptor layer discontinuity diameter 3 months after macular hole surgery. Persistent subfoveal fluid 3 months after macular hole surgery, which was found in 36.5% of eyes, was not associated with a significantly different BCVA after 12 months compared with eyes with a fully attached fovea at 3 months (70.9 letters vs. 72.0 letters; P = 0.59). Receiver operating characteristics curve analysis identified persistent photoreceptor layer discontinuity of a diameter of more than 1477 microm after 3 months to be associated with poorer BCVA after 12 months (P<0.001), yet an overall reduction in discontinuity diameter from 3 to 12 months (P<0.001) was not correlated with a concurrent improvement in BCVA (r = -0.040; P = 0.81). Persistence of fluid and diameter of discontinuity at 3 months were not related to whether ILM peeling was used; however, secondary macular hole surgery had a significant influence on diameter of photoreceptor layer discontinuity at 3 months. Structural recovery in the form of photoreceptor layer discontinuity with a diameter of more than approximately 1500 microm 3 months after macular hole surgery was associated with poorer visual acuity after 12 months than less extensive discontinuity. Subfoveal fluid persisting after 3 months had disappeared after 12 months in all but 5 of 74 eyes and had no effect on final visual outcome.
    Ophthalmology 09/2009; 116(12):2430-6. · 5.45 Impact Factor
  • Article: Macular morphology and visual acuity after macular hole surgery with or without internal limiting membrane peeling.
    [show abstract] [hide abstract]
    ABSTRACT: To examine postoperative macular morphology and visual outcome after 12 months in relation to internal limiting membrane (ILM) peeling versus no peeling, indocyanine green (ICG) staining and re-operation in eyes that achieved macular hole closure after surgery. Seventy-four eyes with closed stage 2 or 3 macular holes were recruited from a randomised clinical trial comparing: (1) vitrectomy without ILM peeling; (2) vitrectomy with 0.05% isotonic ICG-assisted ILM peeling; and (3) vitrectomy with 0.15% trypan blue-assisted ILM peeling. Contrast-enhanced Stratus optical coherence tomography was used to assess central foveal thickness, central photoreceptor layer thickness (CPRT), central photoreceptor layer discontinuity (PRD) and relative reflectivity of the outer nuclear layer. Outcomes were correlated with best corrected visual acuity (BCVA) 12 months after surgery. BCVA was correlated with CPRT and PRD. Regression analysis and receiver operating characteristics curve analysis showed that CPRT >33 microm (OR 12.5) and PRD <177 microm (OR 9.86) were highly predictive for regaining reading vision (> or =69 Early Treatment of Diabetic Retinopathy Study letters) 12 months after surgery. No significant difference was found in postoperative macular morphology between subgroups. Poor vision after 12 months despite macular hole closure was associated with attenuation and disruption of the foveolar photoreceptor matrix. The extent of attenuation and disruption was independent of peeling and staining. Trial registration number: NCT00302328.
    The British journal of ophthalmology 08/2009; 94(1):41-7. · 2.92 Impact Factor
  • Article: Value of internal limiting membrane peeling in surgery for idiopathic macular hole stage 2 and 3: a randomised clinical trial.
    [show abstract] [hide abstract]
    ABSTRACT: To determine the effect of internal limiting membrane (ILM) peeling on anatomical and functional success rates in stage 2 and 3 idiopathic macular hole surgery (MHS). Randomised clinical trial of stage 2 and 3 idiopathic macular hole without visible epiretinal fibrosis and with less than 1 year's duration of symptoms. Eyes were randomised to (1) vitrectomy alone without retinal surface manipulation, (2) vitrectomy plus 0.05% isotonic Indocyanine Green (ICG)-assisted ILM peeling or (3) vitrectomy plus 0.15% Trypan Blue (TB)-assisted ILM peeling. Main outcomes were hole closure after 3 and 12 months and best-corrected visual acuity after 12 months. 78 eyes were enrolled. Primary closure rates were significantly higher with ILM peeling than without peeling for both stage 2 holes (ICG peeling 100%, non-peeling 55%, p = 0.014) and for stage 3 holes (ICG peeling 91%, TB peeling 89%, non-peeling 36%, p<0.001). Visual outcomes in eyes with primary hole closure were not significantly different between the groups. Dye-assisted ILM peeling was associated with significantly higher closure rates than non-peeling in both stage 2 and 3 MHS. Intraoperative ILM staining with 0.05% isotonic ICG was not associated with a significantly different visual outcome than non-peeling or TB peeling in eyes with primary hole closure. Trial registration number: NCT00302328.
    The British journal of ophthalmology 12/2008; 93(8):1005-15. · 2.92 Impact Factor
  • Article: Dissociation of rod and cone sensitivity by acute localized retinal pigment epithelium loss.
    Kristian Krøyer, Morten la Cour, Michael Larsen
    [show abstract] [hide abstract]
    ABSTRACT: To assess the impact of acute retinal pigment epithelium (RPE) loss on photopic and scotopic sensitivity. A 68-year-old woman who had been followed for drusenoid RPE detachment in age-related macular degeneration presented with an acute spontaneous retinal pigment epithelium tear. Three months later, she was seen for routine follow-up and was examined by manual photopic and scotopic threshold perimetry (a static 0.46-degree-diameter 660 nm stimulus under photopic conditions; then, following 25 min of dark adaptation, a static 0.46-degree-diameter 532 nm stimulus under scotopic conditions). The stimuli were applied over the RPE defect and at reference points of similar eccentricity in the opposite vertical haemifield of the same eye where the RPE remained present. Acute RPE loss was associated with only a marginal reduction of photopic sensitivity (-1.5 dB) but a pronounced loss of scotopic sensitivity (-19.5 dB). Our observations show that RPE is essential for scotopic but not for photopic retinal function, supporting the theory that cone photopigment regeneration occurs within the human neurosensory retina independently of the RPE.
    Acta ophthalmologica 06/2008; 86(3):338-40. · 2.44 Impact Factor
  • Article: Objective signs of photoreceptor displacement by binocular correspondence perimetry: a study of epiretinal membranes.
    Kristian Krøyer, Ole Mark Jensen, Michael Larsen
    [show abstract] [hide abstract]
    ABSTRACT: To describe a method for quantitative mapping of metamorphopsia and abnormalities of oculocentric direction in subjects with epiretinal membranes. Binocular correspondence perimetry was performed using red and green dichoptic stimuli applied in a rectangular grid pattern. The study included 9 healthy subjects and 10 subjects with a unilateral premacular epiretinal membrane and a healthy fellow eye. Interocular visuospatial correspondence was expressed in a visuospatial deviation score and the binocular correspondence perimetry plots were displayed in proportion to fundus photographs. A reference interval was defined as the 95% CI for the average visuospatial deviation score in healthy subjects. In 6 out of 10 subjects with epiretinal membranes, visuospatial alignment deviated beyond the reference interval found in healthy subjects, whereas 4 subjects were within the normal range. The deviation score increased with decreasing visual acuity, although indications of heterogeneity of the subject population were identified, suggesting that visual acuity reduction and metamorphopsia may be dissociated in some types of epiretinal membranes. Binocular correspondence perimetry enables quantitative mapping of metamorphopsia and stratification of subjects with epiretinal membranes with respect to normative references. Data from healthy subjects appear to describe a physiological level of tolerance for changes in oculocentric direction, which may apply also to the changes induced by retinal traction.
    Investigative Ophthalmology &amp Visual Science 04/2005; 46(3):1017-22. · 3.60 Impact Factor