Iris Morphology Analisys with Optical Coherence

Tomography for Anterior Segment:

Case report

MENDOZA-VELÁSQUEZ CRISTINA M.D., ARROYO-MUÑOZ LETICIA M.D., GUERRERO-BERGER OSCAR M.D., MACÍAS-

MARTÍNEZ JAIME M.D.

.

FUNDACIÓN HOSPITAL NUESTRA SEÑORA DE LA LUZ. MEXICO CITY

The authors have no financial interest in the subject matter of this e-poster

BACKGROUND

Optical coherence tomography (OCT) was introduced in 1991 to image the posterior segment of the eye. Recently, anterior segment OCT (AS-OCT) has become available. It allows high-resolution, cross-sectional images of the anterior segment and can be used in various clinical situations: investigation of pathological processes in the anterior segment, evaluation of chamber angle configurations and measurement dimensions.1

BACKGROUND

Iris measurements and its morphology can be study with AS-OCT. The results may graphically evidence the alterations in patients with iris specifics features, described only clinically in the past, but now observed and analyzed with a digital image.

Benign prostatic hypertrophy (BPH) and pseudoexfoliation are two pathologies in which are widely described changes in iris morphology.

BPH is a common urologic condition in older men that leads to lower urinary tract symptoms. The usual treatments are the 5-alpha-reductase inhibitors and alpha-1-adrenergic receptor antagonists (alpha-1ARA). The alpha-1ARAs, relax smooth muscle included the iris. These patients had significantly decreased dilatator muscle thickness and smaller pupil diameters.2

BACKGROUND

In pseudoexfoliation, iris changes are an early and consistent feature of the clinical examination. Histologically, there is presence of degenerative changes of the estroma , including the sphincter and dilator muscles. Furthermore, we can observe posterior iris pigment epithelium degeneration with focal membrane ruptures.

OBJECTIVE

Analyze the iris morphology with AS-OCT of patients with clinical alterations of the iris.

MATERIALS

Noninterventional, cross-sectional study adhered to the tenets of the Declaration of Helsinki. Written informed consent was obtained from all subjects.

We prospectively enrolled 6 patients with pseudoexfoliation syndrome and 1 with BPH. AS-OCT were done in both eyes of all patients, evaluating 4 cross-sectional iris (nasal, temporal, superior and inferior) previous topical application of pilocarpine (4 %) 30 minutes before the study. All digital images were analyzed.

MATERIALS

Iris thickness was measured dividing the iris in 3 parts at the digital image obtained in 4 cross-sectional iris (third external, middle and inner temporal and nasal iris).

We used ZEISS Visante TM OCT Model 1000 (VisanteTM OCT software version 2.0.

RESULTS

We analyzed 6 patients with pseudoexfoliation and found that they had slightly greater thickness at temporal iris external third, this area corresponding iris sphincter area.

TIL:TEMPORAL IRIS LENGTH, NIL: NASAL IRIS LENGTH, TIET:TEMPORAL IRIS EXTERNAL THIRD, TIMT: TEMPORAL IRIS MIDDLE THIRD, TIIT: TEMPORAL IRIS INTERNAL THIRD, NIET: NASAL IRIS EXTERNAL THIRD, NIMT: NASAL IRIS MIDDLE THIRD, NIIT: NASAL IRIS INTERNAL THIRD.

THICKNESS IRIS IN PSEUDOEXFOLIATION PATIENTSEYE TIL NIL TIET TIMT TIIT NIET NIMT NIIT

                     0º 5.17 5.00 0.60 0.47 0.48 0.60 0.51 0.49

RIGHT                    90º 5.22 4.90 0.61 0.46 0.40 0.68 0.52 0.43                                        0º 4.77 4.92 0.61 0.51 0.51 0.57 0.48 0.50

LEFT                    90º 5.00 4.94 0.58 0.48 0.49 0.60 0.50 0.48                   

RESULTS

Iris thinning observed in the middle and inner thirds, keeping on whether a uniform thickness throughout the whole extent of the iris.

FIGURE 1,2,3: AS-OCT of a patient with pseudoexfoliation syndrome, we could see the homogeneous iris morphology with slightly thickening in external third.

1

2

3

RESULTS

TIL:TEMPORAL IRIS LENGTH, NIL: NASAL IRIS LENGTH, TIET:TEMPORAL IRIS EXTERNAL THIRD, TIMT: TEMPORAL IRIS MIDDLE THIRD, TIIT: TEMPORAL IRIS INTERNAL THIRD, NIET: NASAL IRIS EXTERNAL THIRD, NIMT: NASAL IRIS MIDDLE THIRD, NIIT: NASAL IRIS INTERNAL THIRD.

We had 1 BPH patient with alpha-1ARA and found an increase in the thickness greater than 0.1 mm in the external third, area corresponding to the iris sphincter.

THICKNESS IRIS IN BPH PATIENTEYE TIL NIL TIET TIMT TIIT NIET NIMT NIIT

                     0º 5.42 5.05 0.59 0.47 0.45 0.59 0.52 0.47

RIGTH                    90º 5.78 5.5 0.67 0.46 0.45 0.75 0.46 0.45                                        0º 4.93 5.27 0.59 0.54 0.47 0.51 0.46 0.49

LEFT                    90º 5.56 5.4 0.67 0.45 0.42 0.69 0.52 0.4                   

RESULTS

In the figures 1, 2, 3 and 4 we could observed the sphincter area thicker than the rest of the iris tissue.

Observed areas of lower density in thickened area in black.

1

2

34

DISCUSSION

There is a difference in iris morphology in patients with a history of alpha-1ARA use as compared with pseudoexfoliation patients.

We need expand the sample and have a control group with age-matched patients. We have digital images of control group but we continue the analyze for its.

In this work we just want to show that the iris morphology is very specific in patients with some pathology.

There are no data in the literature regarding how iris measurements with AS-OCT would correlate with the real iris thickness. However, because all measurements were done using the same device and in the same position for all patients, we believe that it would not significantly alter our results.

The AS-OCT is a widely used tool that provides rapid and objective information regarding anterior segment dimensions and angle configuration. We used it to evaluate iris structural alterations.

REFERENCES

1.- Doors M., Berendschot T., Brabander J., Webers C., Nuijts R. Value of optical coherence tomography for anterior segment surgery. J. Cataract Refract Surg 2010; 36:1213–1229.

2.- Prata T., Palmiero P.M., Angelilli A., Sbeity Z., De Moraes C.G., Liebmann J., Ritch R. Iris Morphologic Changes Related to alpha-1-Adrenergic Receptor Antagonists. Implications for Intraoperative Floppy Iris Syndrome. Ophthalmology 2009;116:877–881.

3.- Schlotzer-Schrehardt U., Naumann G. Ocular and Systemic Pseudoexfoliation Syndrome. Am J Ophthalmol 2006;141: 921–937.

E-mail: cristina_cmv@hotmail.com