J. P. Bergmanson

Collagen fibril characteristics at the corneo-scleral boundary and rabbit corneal stromal swelling.

Background: The aim of this investigation was to reassess the impact of the scleral rim on the swelling of the mammalian corneal stroma and to investigate the ultrastructural features of the scleral rim and corneal stromal tissues.

Heterogeneity in the ultrastructure of the mucous (goblet) cells of the rabbit palpebral conjunctiva

Aim: The purpose of this study was to assess objectively the ultrastructure of the secretory granules in rabbit conjunctival mucin‐producing ‘goblet’ cells.

Vertical imbalance induced by prism-ballasted soft toric contact lenses fitted unilaterally.

Fitting a prism‐ballasted soft toric contact lens unilaterally may potentially induce a vergence error that the subject cannot compensate. In the present study, a prism‐ballasted (1.5Δ base down) soft toric contact lens was fitted in the right eye only of 10 subjects with normal binocular vision. The effect on binocular vision was evaluated by measuring vertical phoria adaptation and vertical fixation disparity adaptation. The results show that the vertical vergence error induced was well compensated and fully adapted to. However, care might be needed when fitting these lenses unilaterally in subjects with vertical phoria‐related problems.

An explanation for the central to peripheral thickness variation in the mouse cornea

Background:u2002 The mouse corneal stroma varies in thickness across its diameter. The purpose of the present study was to explain this variation and to advance our understanding of stromal lamellar architecture in the mammalian cornea.

Size does matter: what is the corneo-limbal diameter?: Corneo-limbal diameter Bergmanson and Martinez

This review surveys available literature for corneal and limbal dimensions. With modern scleral lenses, these measures have become central to determining the overall size of a lens for satisfactory fitting. In general, published values are not based on a definition of what is being measured. In addition, the most widely accepted average corneal diameter measurement, 11.7u2009×u200910.6u2009mm, emanates from one source published more than 50u2009years ago. This value was not based on a measurement but appears to be the cumulative impression of measurements from seven studies conducted between 67 and 127u2009years ago. Furthermore, in most instances, if at all stated, quoted measures are based on horizontal visible iris diameter, providing limited acknowledgement of limbal width and its inclusion as part of the corneal diameter. The corneo-scleral sulcus from one side to the other has been measured, giving a larger diameter, but may include at least part of the limbus. More objective measurements are possible with modern ophthalmic instrumentation but the lack of structural definition and low magnification resolution with these techniques raises concerns with the accuracy of the results. Measurement of the horizontal visible iris diameter does not include the limbal width, which means that the horizontal visible iris diameter is an underestimate of the true corneo-limbal diameter. This review concludes that the width of the limbus has been neither structurally defined nor accurately measured and that there is a need for the development of new protocols for determining the dimensions of the average cornea and limbus. It is predicted that more accurate measures will indicate that to vault across cornea with limbus and provide excellent comfort, the average cornea will need a lens to have a diameter of 16.0u2009mm or larger.This review surveys available literature for corneal and limbal dimensions. With modern scleral lenses, these measures have become central to determining the overall size of a lens for satisfactory fitting. In general, published values are not based on a definition of what is being measured. In addition, the most widely accepted average corneal diameter measurement, 11.7u2009×u200910.6u2009mm, emanates from one source published more than 50u2009years ago. This value was not based on a measurement but appears to be the cumulative impression of measurements from seven studies conducted between 67 and 127u2009years ago. Furthermore, in most instances, if at all stated, quoted measures are based on horizontal visible iris diameter, providing limited acknowledgement of limbal width and its inclusion as part of the corneal diameter. The corneo‐scleral sulcus from one side to the other has been measured, giving a larger diameter, but may include at least part of the limbus. More objective measurements are possible with modern ophthalmic instrumentation but the lack of structural definition and low magnification resolution with these techniques raises concerns with the accuracy of the results. Measurement of the horizontal visible iris diameter does not include the limbal width, which means that the horizontal visible iris diameter is an underestimate of the true corneo‐limbal diameter. This review concludes that the width of the limbus has been neither structurally defined nor accurately measured and that there is a need for the development of new protocols for determining the dimensions of the average cornea and limbus. It is predicted that more accurate measures will indicate that to vault across cornea with limbus and provide excellent comfort, the average cornea will need a lens to have a diameter of 16.0u2009mm or larger.

Evaluation of the anterior chamber angle in keratoconus and normal subjects.

PURPOSEnTo evaluate the anterior chamber angle in keratoconus eyes by use of the Visante™ OCT and Orbscan™ II.nnnMETHODSnAnterior chamber angle was measured with the Visante™ OCT and Orbscan™ II in 52 subjects, 26 KC subjects and 26 age and control subjects.nnnRESULTSnWhen comparing the nasal and temporal angles obtained with the two techniques no correlation was found (R(2) always below 0.01) in either the control subjects or in the KC subjects. Despite this, there was an overall statistically significant difference in mean anterior chamber angles (p<0.001) between Visante™ OCT and Orbscan™ II. There was no statistical difference (p>0.05) between nasal and temporal anterior chamber angles when comparing controls and KC subjects with either of the two instruments. In general, the Visante™ OCT gave a smaller estimate of the anterior chamber angle.nnnCONCLUSIONnThe values from the Visante™ OCT and Orbscan™ II cannot be interchanged since the difference in measurement of the anterior chamber angle was significantly different between the two instruments.

Comparison of Macular Thickness in Patients with Keratoconus and Control Subjects Using the Cirrus HD-OCT

Purpose. The aim of the present study was to compare macular thickness in patients with keratoconus (KC) with macular thickness in healthy subjects. Subjects and Methods. Twenty-six patients with KC and 52 control subjects were included. The macular structure was evaluated using a Zeiss Cirrus HD-OCT. The scan pattern used was 512 × 128, which covers an area of approximately 6 × 6u2009mm of the retina. The cube volume was assessed as well as macular thickness in each of the 9 sectors defined by the software. Results. The mean signal strength was significantly lower in the KC group (mean 8.4, range 6–10) compared with the control group (mean 9.7, range 7–10), P < 0.0001 (unpaired t-test). There were no significant differences in cube volume (unpaired t-test), cube average thickness, or macular thickness between the KC group and the control subjects in any of the retinal locations (one-way ANOVA). Conclusion. Macular structure as measured by OCT in KC subjects should be expected to lie within the range of age and sex matched controls.